Early morning and midday body temperatures of rams and ewes of three breeds of sheep were measured once weekly for a period of 10 months in Northern Rhodesia and 12 months in Southern Rhodesia.

1. In all breeds seasonal fluctuations in body temperature were due to concurrent fluctuations in ambient air temperature.

2. Mean annual body temperatures were: Merino 102·2° F.; Persian 101·7° F. and Native 101·7° F. Wool and hair breeds differed considerably in their early morning temperatures and in their body temperature increases from 6.30 a.m. to 12.30 p.m. Mean annual values for these measurements were Merino 101·73 and 1·92° F.; Persian 100·81 and 1·83° F.; Native 100·73 and 1–92° F. At all times Merinos showed markedly greater uniformity of body temperature than either hair breed. There was no evidence to show that the thermoregulatory mechanisms of these animals had been stressed unduly.

3. Sex had no consistent effect on body temperature or on rise in body temperature.

In general, lactating ewes showed a significantly higher initial body temperature than either empty or pregnant ewes, but the respective heat tolerances as measured by body temperature increase did not differ appreciably. Body temperature differed little in empty and pregnant ewes.

4. Although the youngest group of ewes in each breed showed the highest early morning temperature, there was no evidence that heat tolerance was less in young than in old animals.

5. Black-coated Native ewes had higher initial body temperatures and a smaller body temperature increase during the summer months in Southern Rhodesia than brown or broken-coloured Native ewes. These effects were due to differences in coat density rather than to differences in coat colour or skin pigmentation.

6. In all breeds the magnitude of the diurnal and annual variation in body temperature was different in Northern and Southern Rhodesia. Differences were largely of climatic origin but low plane of nutrition in Southern Rhodesia possibly reduced critical body temperature and impaired thermoregulatory ability.

Article by van Tienhoven: ‘Metabolism of fowl sperm on different diluents.’

Tables 1–17: in column headed ‘Source’ read ‘replication’ for ‘respiration’.

In the communication: ‘Studies of the skeleton of the sheep. IV. The effects and interactions of dietary supplements of calcium, phosphorus, cod-liver oil and energy, as starch, on the skeleton of growing blackface wethers’, D. Benzie, A. W. Boyne, A. C. Dalgarno, J. Duckworth, R. Hill & D. M. Walker, J. Agric. Sci. (1960), 54, 202–221, Plates A1, A2 and B1, B2 have been interchanged on Plate 9. The letters A, B and C have been omitted from Plate 10, and should read top, middle and bottom respectively.

The average yields of irrigated long-staple cotton in the three-course rotations: dura, fallow, cotton, D-F-C; lubia, fallow, cotton, L-F-C; and fallow, fallow, cotton, F-F-C, were studied over 12 years in an experiment in the Sudan Gezira; the fallows (resting land) were either hoed or were left uncultivated during the rainy season, so that the effects of the operation of hoeing on the subsequent cotton yields could be measured.

Where the fallows were unhoed L-F-C yielded more cotton than F-F-C, which gave at first higher yields than D-F-C, although this difference had disappeared by the end of the period. Fallow hoeing increased yields in all rotations; this response was maintained in D-F-C and L-F-C. In F-F-C the response to hoeing either fallow diminished steadily in time and whilst the higher response to hoeing both fallows also decreased, its rate of decrease was no greater than when only one fallow was hoed. The response to hoeing fluctuated considerably from year to year. In all rotations these fluctuations were associated with rainfall and the relationships have been expressed in the form of regression equations; separate equations were necessary for each rotation as the relationships were quite distinct.

The variety X1730 A out-yielded Domains Sakel. There were interactions between the varieties and the other treatments, but these interactions were such that the varieties differed more at higher levels of yield and did not modify the above conclusions appreciably.

An artificial rumen is described which has been shown to simulate closely conditions in the bovine rumen. Criteria of its validity include quantitative and qualitative bacteriological data, V.F.A. production, pH levels and digestion rates; these were examined with a variety of diets using cows on similar diets as controls. An important feature of the apparatus is the high degree of control which can be exercised over the progress of the in vitro ruminal fermentation, permitting experiments of considerable duration.

1. Twenty-two experiments on main-crop potatoes in 1955–7 compared calcium nitrate and ammonium sulphate applied to the seedbeds before planting. Urea was also tested in fifteen of the experiments in 1956–7. The three fertilizers were compared at rates that supplied 0·5, 1·Oand 1·5 cwt. N/acre.

2. Seven experiments on kale in 1955–8 compared seedbed dressings of calcium nitrate and ammonium sulphate. Urea “was also tested in. five of the experiments in 1956–8. The rates used were 0·6, 1·2 and 1·8 cwt. N/acre in 1955 and 1·0 and 2·0 cwt. N/acre subsequently. Single dressings applied to the seedbed were also compared with divided dressings applied partly to the seedbed and partly in mid-season.

3. Generally the potatoes gave only small responses to N; there was no worthwhile gain from applying more than 1·0 cwt. N/acre in 1955 and 0·5 cwt. N in 1956 and 1957. Nitrogen gave much larger proportionate increases in yields of kale, at several of the centres crops continued to respond up to dressings of 2·0 cwt. N/acre.

4. Calcium nitrate generally gave lower yields of potatoes than ammonium sulphate and the superiority of ammonium sulphate was greater with the higher dressings. Losses in yield with the nitrate were usually associated with a severe check to early growth occurring in dry springs and with dressings concentrated close to the seed, but lower yields were also obtained at some centres where early growth was not damaged. Calcium nitrate and ammonium sulphate were roughly equivalent for kale when the nitrate did not damage germination; heavy seedbed dressings of the nitrate reduced kale plant numbers severely unless there was adequate rain after sowing.

5. Granulated urea tested in 1956 contained 4·5% of biuret, it delayed emergence and reduced plant establishment seriously in several of the potato experiments; damage increased with the level of manuring and was accentuated when dressings were broadcast over furrows before hand-planting. Yields given by this batch of urea were less than with other N fertilizers and when 1·5 cwt. N/acre was applied they were less than with no nitrogen at all. Purer crystalline urea (having less than 1% of biuret) used in the 1957 experiments caused no damage to emergence of potatoes and gave yields similar to those obtained with ammonium sulphate. There were similar effects in the kale experiments; granulated urea containing much biuret damaged germination severely in 1956; the purer products containing little biuret used in later years reduced plant numbers at one centre in 1957 and at the single 1958 centre. Where there was no damage to the establishment of kale, urea and ammonium sulphate gave similar yields.

6. Dressings applied partly to the seedbed and partly in mid-season gave slightly higher average yields of kale than an equivalent total amount of nitrogen all applied before sowing.

Responses in body, skin and coat temperatures, cardio-respiratory frequencies and rate of moisture secretion of ewes of three breeds to the diurnal fluctuation in ambient temperature were recorded in the presence and absence of drinking water during the hottest part of the Rhodesian year.

1. At 7.0 a.m. body temperatures were: Merino 102·8° F.; Persian 102·2° F. and Native 101·5° F. Between 7·0 a.m. and 1·0 p.m. body temperature rose almost equally in Persians and Natives and fell slightly in Merinos. Change in body temperature between 7.0 a.m. and 1.0 p.m. was not affected significantly by availability of water nor age of ewe, but varied with type of thermal burden (i.e. solar insolation only v. solar insolation plus artificial heat) when water was not available. Although air temperature fell towards late afternoon body temperature of Merinos and Natives rose appreciably, that of Persians only slightly.

2. At 7·0 a.m. respiratory rates were (cyc./min.): Merino 59·6; Persian 43·0; Native 29·9. Increase in rate of respiration was the main thermolytic mechanism in all breeds. Merinos had a lower threshold of respiratory response to rising ambient temperature than either hair breed but increase in rate of respiration between 7.0 a.m. and 1.0 p.m. did not differ significantly with breed or age.

3. No breed appeared to use the peripheral blood system in thermoregulation. Cardio-frequency, as a measure of this blood flow, remained almost constant with a slight tendency to fall with rise in ambient temperature.

4. In all breeds skin temperature was related to ambient and body temperatures; consequently the diurnal fluctuation in skin temperature differed in wool and hair breeds. When thermal burden was greatest Merino skin temperature fell, that of hair breeds did not.

Except at 11.0 a.m. there was a gradient between rectal, skin and air temperatures. Direct elimination of heat was thus possible for 23 hr. each day.

5. In hair breeds moisture secretion depended on insensible perspiration; consequently, rate of moisture secretion changed with body and air temperatures. In Merinos moisture for skin surface evaporation was provided by sensible and insensible perspiration. Natives may be able to sweat at temperatures higher than those recorded but it is unlikely Persians have a sweating mechanism.

6. In all breeds coat temperature was related closely to ambient temperature and changes in solar conditions evoked immediate response in coat temperature. Merino fleece apparently stabilized skin temperature whereas Persian and Native hair did not.

1. Ten manurial treatments were applied annually to cattle cabbage grown in a six-course rotation for 7 years. Samples were taken in the early winter each year, and from five harvests taken at fortnightly intervals in the last year.

2. The dry-matter yields each year closely followed the weather conditions during the growing season. There was no significant fall in the dry-matter yield during the last season. The treatments supplying phosphorus or phosphorus and potassium substantially increased yield, but the application of nitrogen did not.

3. The application of nitrogen, potassium or phosphorus increased the levels of these constituents in the crop in practically all cases. The application of phosphorus produced hearted plants which contained significantly less dry matter than the openleavod plants produced in its absence. The levels of ether extract, crude fibre, ash, silica and magnesium wore not significantly affected by the manorial treatments.

4. There was little variation in composition as the season advanced except for significant increases in the crude-fibre levels and decreases in the nitrogen-free extractives levels.

5. The distribution of the chemical components was investigated in the outer leaves, heart leaves and stem of the plant. This was compared with that in the marrow-stem kales.

6. The chemical composition of the cattle cabbage compares fairly closely with that found for the marrow-stem kales grown under similar conditions. It is, however, lower in dry matter, crude fibre, magnesium and chlorine. It may be considered as a replacement for marrow-stem kale as a source of crude protein and all the major minerals except chlorine and possibly magnesium.

Mature and young Merino, Persian and Native rams were compelled to run 1 mile in 10–12 min. The response to the thermal burden induced by this exercise was measured in terms of body and skin temperatures, rate of respiration and length and temperature of the scrotum.

1. Marked increases were recorded in every body response immediately after the exercise. Body, skin and scrotal temperatures returned to normal within 2 hr. but respiratory rate remained elevated for a further 4 hr.

2. There were breed differences in the initial and subsequent measurement of every response. At 7.0 a.m. when there was no thermal stress body temperatures and rates of respiration were: Merino 102·9° F.; 3·-6 cyc./min. Persian 101·4° F.; 23·8 cyc./min. Native 102·1° F.; 28·9 cyc./min. Merino rams had the greatest ability to combat rising ambient temperature, Native rams the least. Persian rams recuperated quickest after exercise, Native rams slowest. The different responses of wool and hair breeds were apparently due to their coats. Merino fleece stabilized body temperature, did not aggravate the effects of exercise unduly and did not greatly hamper elimination of heat from the body after exercise.

3. In all breeds respiratory evaporation was the principal thermolytic process. Rate of respiration was a sensitive indicator of thermal stress but it could not be used as an index of heat tolerance because the associated changes in respiratory volume were not known.

4. Age was seldom of significant importance to determine response to thermal burden. In general young rams were affected less adversely by exercise and more adversely by rising ambient temperature than were mature rams. These differential effects were probably due to leggy conformation, low live weight and physical fitness in young rams on one hand, and incomplete development of the thermoregulatory system on the other.

5. Increase in scrotal pendulance was related inversely to ability to maintain normal body temperature.

6. In view of the influence of age and body conformation on the response to exercise it was questioned whether comparable heat tolerance indices could be obtained by this method.

1. The reliability of the Kjeldahl method for the determination of nitrogen in soils has been investigated using a range of soils containing from 0·03 to 2·7% nitrogen.

2. The same result was obtained when soil was analysed by a variety of Kjeldahl procedures which included methods known to recover various forms of nitrogen not determined by Kjeldahl procedures commonly employed for soil analysis. From this and other evidence presented it is concluded that very little, if any, of the nitrogen in the soils examined was in the form of highly refractory nitrogen compounds or of compounds containing N—N or N—O linkages.

3. Results by the method of determining nitrogen in soils recommended by the Association of Official Agricultural Chemists were 10–37% lower than those obtained by other methods tested. Satisfactory results were obtained by this method when the period of digestion recommended was increased.

4. Ammonium-N fixed by clay minerals is determined by the Kjeldahl method.

5. Selenium and mercury are considerably more effective than copper for catalysis of Kjeldahl digestion of soil. Conditions leading to loss of nitrogen using selenium are defined, and difficulties encountered using mercury are discussed.

6. The most important factor in Kjeldahl analysis is the temperature of digestion with sulphuric acid, which is controlled largely by the amount of potassium (or sodium) sulphate used for digestion.

7. The period of digestion required for Kjeldahl analysis of soil depends on the concentration of potassium sulphate in the digest. When the concentration is low (e.g. 0·3 g./ml. sulphuric acid) it is necessary to digest for several hours; when it is high (e.g. 1·0 g./ml. sulphuric acid) short periods of digestion are adequate. Catalysts greatly affect the rate of digestion when the salt concentration is low, but have little effect when the salt concentration is high.

8. Nitrogen is lost during Kjeldahl analysis when the temperature of digestion exceeds about 400° C.

9. Determinations of the amounts of sulphuric acid consumed by various mineral and organic soils during Kjeldahl digestion showed that there is little risk of loss of nitrogen under the conditions usually employed for Kjeldahl digestion of soil. Acid consumption values for various soil constituents are given, from which the amounts of sulphuric acid likely to be consumed during Kjeldahl digestion of different types of soil can be calculated.

10. Semi-micro Kjeldahl methods of determining soil nitrogen gave the same results as macro-Kjeldahl methods.

11. The use of the Hoskins apparatus for the determination of ammonium is described.

12. It is concluded that the Kjeldahl method is satisfactory for the determination of nitrogen in soils provided a few simple precautions are observed. The merits and defects of different Kjeldahl procedures are discussed.

1. A co-ordinated trial has been carried out at eighteen centres to study the effects of feeding various quantities of high-protein supplement to growing-fattening pigs. In treatment 1, 10% white fish meal was included from weaning to 150 lb. live weight and 3% soya-bean meal was included from 150 lb. live weight to slaughter (approximately 210 lb.). Treatment 2 was the same as treatment 1 except that only 7% white fish meal was included during the first stage. Treatment 3 was the same as treatment 2 except that the rations were changed at 1001b. live weight instead of 1501b. Treatment 4 was the same as treatment 3 except that highprotein supplement was omitted altogether after 1501b. live weight; thus there were three rations involved in treatment 4—7% white fish meal from weaning to 100 lb. live weight, 3% soya-bean meal from 100 lb. to 150 lb. and no high-protein supplement thereafter.

2. Growth rate and feed conversion both differed significantly between treatments. Pigs on treatment 1 grew 5·0% faster than those on treatment 4; the average growth rate for treatments 2 and 3, the difference between which was negligible, was 3·3% higher than for treatment 4. Feed conversion for treatment 1 was 5·4% better than for treatment 4 and the average for treatments 2 and 3 was 3·8% better than for treatment 4.

3. Treatment differences were not significant for killing-out percentage, length, quality of fat, proportions of gammon, middle and fore-end of the cured side, thickness of streak, size of eye muscle and amount of fat over it. Some of the fat measurements differed significantly between treatments; differences in fat thickness at the shoulder, middle and rump between treatments 1, 2 and 3 were generally small, but the lowest protein level (treatment 4) resulted in carcasses with about 2% more fat along the back than the average of treatments 1, 2 and 3. These slight differences in back-fat thickness did not result in significant differences in the percentage of pigs in the highest grades.

4. An economic appraisal of the results suggested that under the conditions prevailing at the time of the experiment treatment 3 would have resulted in the greatest profit per year, and the greatest profit per pig. This ration was relatively cheap compared with those of treatments 1 and 2 but it did not lead to a seriously impaired performance, as did that of treatment 4, the cheapest ration.

The influence of fleece on thermoregulation in German Merino ewes was investigated in Rhodesia. Comparative heat tolerances of Persian Blackhead, indigenous Native and shorn and unshorn Merino ewes were obtained during the hottest month of the year in Northern Rhodesia. The main thermolytic responses in unshorn, partially shorn and completely shorn Merino ewes were measured at 7.0 a.m.; 10.0 a.m.; 1.0 p.m. and 4.0 p.m. during April in Southern Rhodesia.

1. Unshorn Merino ewes showed more and shorn Merino ewes less effective body temperature regulation than Persian or Native ewes. High heat tolerance in unshorn Merinos was due primarily to insulation by the fleece and not to more efficient physiological thermolysis than in hair breeds. No ewe showed signs of undue thermal stress and feed intake was not affected by heat.

2. Increases in rectal temperature and respiratory rate between 7.0 a.m. and 1.0 p.m. of Merinos in Southern Rhodesia were related inversely to fleece length. Body temperature did not differ significantly at 1.0 p.m. owing to differential rates of increase in respiratory rate.

3. Magnitude of the diurnal fluctuation in skin temperature was also related inversely to fleece length. Partially shorn ewes, however, began with and maintained highest skin temperature through the heat of the day. In all groups skin temperature fell after 10.0 a.m. although ambient temperature continued to rise. This fall could not be attributed to sweating since moisture secretion declined simultaneously.

A study, using the methods of growth analysis, is reported of the accumulation of dry matter in two Natal Common groundnut crops grown at Kongwa, Tanganyika under conditions of relatively low population (26,000 plants/acre) with phosphate fertilizer (F series), and at a higher population (56,000 plants/acre) without fertilizer (O series). The uptake and distribution of N, P, K, Mg and Ca was followed in the F series.

In the F series, the dry weight per plant at maturity was 32·7 g., of which 14·9 g. (45%) was kernels, while in the O series the corresponding figures were 20·6 and 10·4 g. The relative growth rates, net assimilation rates and leaf-area ratios were similar in the two crops, with small but consistent advantages to the F series. Nevertheless, the yields per acre were markedly higher in the O series, where total dry-matter and kernel yield were 2540 and 1290 lb./acre, respectively, against 1910 and 870 lb. in the F series. It is shown that this was the result of consistently higher leaf weights per acre and a higher total leaf-weight duration (4180 lb. weeks/acre) in the O series than in the F series, where total leaf weight duration was 2810 lb. weeks/acre.

The formation of the kernels continued to maturity in each case, largely at the expense of current assimilation rather than by net translocation from the vegetative parts.

The uptake of N, in the F series, reached a total of 63 lb./acre, of which 45 lb. was in the mature kernels. It went largely into the vegetative parts during the first two-thirds of the crop's life, but in the final stages most of the uptake went into the kernels and there was some evidence of translocation of N from the vegetative parts and the shells. N accumulation did not seem to be affected by rainfall fluctuations within the season. The net assimilation rate did not appear to be directly associated with the activity of the plant in accumulating N, but the leaf-area ratio, and the relative growth rate, were associated with the rate of N uptake per unit of plant dry weight.

The total P taken up was no more than 4 lb. (of the element) per acre of which nearly 80% was found in the kernels at maturity. There was considerable evidence of translocation of P into the kernels from the vegetative parts of the plant. P uptake (unlike that of N) was heavily reduced in a mid-season dry period, suggesting that P was largely derived from the upper layers of the soil.

The total amount of K found in the crop at maturity was about 26 lb./acre, mostly in the vegetative parts. Rather under a fifth was in the kernels, although they constituted 45% of the total dry weight. The data for Ca and Mg are incomplete, but it may be suggested that the maximum accumulation of Ca was around 10 lb./acre, almost all in the vegetative parts, and that of Mg about 5 lb./acre, of which 2 were in the kernels.

The grateful thanks of the authors are due to Dr M. T. Friend, of the East African Agriculture and Forestry Research Organisation, Muguga, Kenya, who determined N and P in the samples of the F series, and to Mr G. T. Chamberlain, of the same Organisation, who carried out the estimations of K, Ca and Mg. They would also wish to express their indebtedness to the members of the former Scientific Department of the Overseas Food Corporation who assisted with the work in laboratory and field, and in particular to Mr B. W. Culy, Manager of the Kongwa Experimental Station, who was responsible for the production of the crops.

An analysis has been made of the reproductive rates and milk yield of Kenana cattle in a closed dairy herd in Sudan.

The average age at first calving was 38·4 months and calvings were most frequent between September and December.

The average length of productive herd life of cows was 5·42 lactations.

The average interval between successive calvings was 395 days, and this was influenced by years and age.

The mean generation interval was 6·72 years.

The average milk yield in 224 days was 338 gal. with a standard deviation of 152 gal.

There was a close relationship between milk yield and lactation length; r = 0·866 ± 0·013.

Milk yield increased by age until the fourth lactation when it was about 137% of the first lactation. The rate of increase in yield between first and second lactation was highest and amounted to 22%.

Year of record had a pronounced effect on milk yield.

Month of calving had a slight effect on milk yield.

The repeatability estimates of single records milk yield, calving intervals, lactation periods and dry periods were 0·432 ± 0·046, 0·058 ± 0·059, 0·192 ± 0·058 and 0·069 ± 0·065, respectively.

The increase in repeatability estimates between earlier and later successive milk yield records was accompanied by a decrease in the coefficients of variation of these records.

The heritability of a single record milk yield was 0·239 ± 0·245.

The rate of annual genetic superiority in milk yield of dams of cows and dams of bulls was found to be 0·74% of the herd average.

Nitrification of urea and its loss through the volatilization of NH3 were studied under different soil conditions. Under all conditions less urea was nitrified and more time was needed for its nitrification in sandy than in sandy loam soil. Nitrification was favoured at lower concentration of urea, onethird moisture of the moisture-holding capacity and at neutrality or the alkaline pH.

Loss of NH3 was found to be twice as much from the sandy loam as from the sandy soil. It was also found that half of the total loss occurred during first drying. Loss of NH3 from urea was found to be proportional to its concentration. The loss increased with the increase in soil moisture and temperature; but it decreased with the decrease in pH on the acid side and the increase in depth of its placement.

Three different stocks of mice were selected for five generations for high body weight at 3, 4½, or 6 weeks of age. Changes in body weight at the three ages and in abdominal fat weight, an index of carcass composition, which occurred in the three lines were compared. It was found that the proportion of fat in the carcasses of the selected animals increased markedly in the lines selected for high 3-week weight, while in the other two lines the proportion remained the same as that in the control line.

The theoretical treatment of the genetic relationship between body weights at different ages and between body weight and abdominal fat was reasonably adequate in accounting for the correlated responses actually observed.

1. Italian ryegrass, laid down for two years, was used to compare the value of casein and formalized casein, ammonium sulphate, calcium nitrate and urea for grassland production. Residual effects of these treatments were measured on a third-year crop of barley.

2. Single dressings of ammonium sulphate and casein were of similar value at each of three cuttings in 1956.

3. Casein treated with formalin released nitrogen much more slowly and was of little value in the early part of the growing season. Formalized casein produced significantly higher yields than casein at the later cuttings in both years, but aggregate increases from this material were much lower than those obtained from untreated casein in each season. Formalized casein increased yields considerably in the year following application.

4. Single dressings of formalized casein were also compared with ‘repeated’ dressings of ammonium sulphate, calcium nitrate and urea, in which the same total quantity of nitrogen was divided equally between cuttings. Formalized casein produced much lower yields than these ‘repeated’ dressings in the early part of the season, but was of only slightly less value at the last cut in 1956 and gave the highest yield at the final cut in 1957. Aggregate yields from repeated dressings of inorganic N fertilizers were higher than those given by single dressings of either form of casein.

5. Comparisons were also made between the yields given by ammonium sulphate, calcium nitrate and urea. Urea applied before sowing (at 0·5 cwt. N/acre) damaged germination and reduced plant establishment slightly. Under dry conditions both urea and calcium nitrate tended to give higher yields than ammonium sulphate but with adequate rain all three fertilizers gave similar yields.

A study has been made of all eggs laid over a year (March-March) by twelve birds.

It was found that:

1. Shell thickness, yolk weight and white weight all increased with time.

2. For each individual bird a linear relationship existed between yolk weight and yolk calcium weight and between yolk weight and yolk phosphorus weight.

3. High calcium diets significantly increased shell thickness at the beginning of the experiment and yolk calcium around the middle of the experiment. Dietary calcium levels had no other effects and dietary phosphorus levels no effects at all.

4. The ‘curves’ relating shell thickness and time for each individual bird are discussed in relation to the relative merits of different birds as producers of thick shells.

1. Activity of Lumbricus terrestris, Allolobophora caliginosa and A. chlorotica was unaffected by 15 mg. hexoestrol in solution in 500 g. soil.

2. Activity and reproduction of A. caliginosa was unaffected by 10 mg. hexoestrol in 500 g. soil, but 100 mg. and over affected activity and stopped reproduction.

3. Egg capsules of A. caliginosa and A. chlorotica developed normally in a saturated aqueous solution of hexoestrol.

4. No effect on the soil fauna of grass plots due to grazing with implanted bullocks was observed.

This paper describes an experiment designed to test the goitrogenic effect of white clover (Trifolium repens L) in ewe lambs grown and taken through a complete reproductive cycle. The sheep were setstocked on four pastures made up of perennial ryegrass and short-rotation rye-grass, both alone and together with cyanogenetic white clover. Since these species differ in iodine content when grown on the same soil, there were probably differences in dietary iodine intake of the sheep in the four groups. Half the animals in each group were injected intramuscularly with an iodinated poppy-seed oil to serve as an iodine depot.

At slaughter, 19 months from the commencement of the experiment, thyroid weights indicated a goitrogenic action in the non-injected ewes grazing short-rotation rye-grass and white clover and to a lesser extent in the non-injected ewes grazing perennial rye-grass and white clover. There was evidence of a slight goitrogenic action in noninjected ewes grazing perennial rye-grass. The thyroids of non-injected ewes had similar iodine contents, lying within the range of 0·23–0·29% of the dry weight.

In injected ewes, the total iodine content of the serum was three to four times higher than with non-injected ewes and the iodine content of the thyroids was three times greater. All injected ewes had thyroids of normal weight.

No effects of iodine supplementation on growth, reproduction or wool production were found.

Lambs born to the ewes in the fifteenth month of the experiment were slaughtered when 3–5 months old, the age varying with pasture treatment. Thyroid weights indicated a goitrogenic effect from the clover-containing pastures.

1. The apparent cleanliness of the premises in which chicks are reared has little bearing on the growth rate of chicks within a given environment.

2. Bacterial counts of faeces from chicks reared under clean or extremely contaminated conditions showed no difference between the two sets of conditions.

3. Delaying feeding until 72 hr. after hatching retarded growth to at least 7 weeks of age. If the age of the chicks was calculated from the time at which the chicks were fed rather than the date of hatch, the weights of the chicks fed 72 hr. after hatching corresponded with those of the chicks fed immediately.

4. The contents of the duodenum and mesenteric intestine showed higher bacterial counts when feeding was delayed for 72 hr. than when feed was given shortly after hatching. This effect was no longer evident after the chicks were 1 week old.

5. Administration of penicillin in the water did not reduce the difference in growth rates between the chicks given feed immediately and those from which feed was withheld.

6. Antibiotics may decrease the thickness of the intestinal wall without stimulating growth.