The species of the genus Ancylostoma (Dubini, 1848) reported as parasites of the human intestine are A. duodenale, A. braziliense, and occasionally A. caninum and A. malayanum. “Creeping eruption ” is considered to be a cutaneous helminthiasis produced by larvae of an ancylostome that American authors accepted as A. braziliense. As a result of detailed studies of the parasite by Lane (1922), Darling (1924) and Schwartz (1927), the majority of parasitologists now treat A. ceylanicum as a synonym of A. braziliense, contrary to the opinions of de Faria (1914,1916) who described A. braziliense, and Looss (1914) who described A. ceylanicum. The solution of the problem is not only of systematic but also of epidemiological importance because de Faria (1914) expressed the opinion that A. braziliense is not pathogenic for man. In the present enquiry the writer has been able to demonstrate that A. braziliense and A. ceylanicum are two different species; and for this reason it is considered of interest to summarise the original descriptions of the two nematodes and the existing opinions concerning this problem.

In 1911 Looss wrote as follows : “ Up to the present time Agchylostoma duodenale is known to occur with certainty only in Man. It is true that the older works and text-books state that it has also been found in various species of animals (some species of apes, the tiger, the dog, the horse, etc.). In opposition to these statements, attempts made on various occasions to infect adult dogs, cats, rabbits, guineapigs, rats, mice, etc., with the parasite yielded entirely negative results. Only with quite young dogs and cats (not more than three or four months old) was the infection partly successful. The results of all these attempts at artificial infection thus support the view that the older statements as to the natural occurrence of Agchylostoma duodenale in animals are founded on a confusion of this species with others …”

1. A new Dicrocoelid trematode, Leipertrema rewelli n.g., n.sp., from the pancreas of an Orang Utan which died in the London Zoological Gardens, is described, and the relationships to other genera are discussed.

2. A male and female Dirofilaria from the peritoneal cavity of the Orang Utan are described and identified as D. immitis (Leidy, 1856).

3. Reasons are advanced for the view that D. pongoi Vogel and Vogelsang, 1980, is a synonym of D. immitis.

During March, 1950, the writers visited a 15-acre field of mixed oats and vetches near Lechlade, Gloucestershire, because it was reported that the crop was patchy and that both oats and vetches were diseased. Inspection of the field revealed typical “tulip-root” symptoms in the oats, while many of the vetches were severely dwarfed and showed browning of the lower parts of the stems. Subsequent examination of plants in the laboratory showed the presence of large numbers of Ditylenchus dipsaci in the oats and a rather lighter infestation in the vetches; in the latter the eelworms seemed to be associated particularly with the necrotic tissues in the lower parts of the stems. It may also be mentioned that young docks, probably Rumex crispus L., from the same field were found to contain D.dipsaci.

The finding of tares or common vetch, Vida sativa L., attacked by the stem eelworm, Ditylenchus dipsaci (Kiihn) Filipjev, reported in the foregoing paper by Staniland and Southcy and the correspondence on the subject which passed between Staniland and Goodey, brought to light an interesting point in regard to the accuracy of the first record of the parasite on this particular host which calls for some comment and elucidation.

During the detailed study of the finer anatomical structure of the potato tuber nematode, Ditylenchus destructor Thome, 1945, the presence of an apparently hitherto unrecorded structure was revealed. It is situated on the ventral surface of the body just anterior to the excretory pore. It is quite easily seen in living nematodes and has no doubt, in the past, been confused with the excretory pore. It appears as a bright lens-like structure, more highly refractive than the neighbouring parts, especially when specimens are viewed in an approximately lateral position. The structure is really band-like, usually more or less biconvex in section, situated between the cuticle and hypodermal layer.

The foregoing results throw light on the conditions under which hatching tests can be carried out. In the first place, pre-soaking cysts in water for a period of 10 days increases the rate of larval emergence but has no effect on the total number of hatchable larvae. Increase in temperature has a similar effect up to 25°C, but at 80°C. hatching is virtually inhibited. Volume of diffusate per cyst is without effect either on the number of hatchable larvae or on their rate of hatching. Neither was any effect observed from alterations in pH between 8.2 and 8.1. The effect of dilution is more or less linear when dilution is plotted geometrically against cither the number of hatchable larvae or the latter expressed as a proportion of the original cyst contents and subjected to angular transformation. For the effect to be appreciable, dilution must be of a high order. Dilution to a half or a quarter of the original concentration has little appreciable effect. The effect of dilution on the rate of hatching is not obvious and the variations in it resulting from dilution are probably random. Direct sunlight inhibits hatching, diffused daylight is without effect as compared with darkness ; cysts exposed to the action of sunlight and diffusate do not hatch when later removed to the dark. It appears reasonable to assume that this may be due to some lethal effect.

Immersion of cysts of Heterodera rostochiensis in potato-root diffusate results in larval emergence which may occupy up to two or three months. In a previous paper (Fenwick, 1950), the author dealt with the form of the hatching curve, and showed that any given curve was controlled by three parameters; the number of larvae finally emerging, the mean reaction time of the hatchable larvae and the standard deviation of that mean reaction time expressed in log-time units. Since it was also shown that each of these parameters was subject to considerable variation, it is obvious that maximum information and accuracy can only be obtained by continuing a hatching test until all larval emergence has ceased and plotting cumulative hatches at selected intervals of tune against log-time; in this way detailed information may be obtained regarding the parameters of the hatching curve.

In their preliminary paper (Fenwick and Franklin, 1942) on the identification of the cyst-forming species of the nematode Heterodera by means of the length of the larvae, the present authors studied methods of preparing the larvae for measurement and of making the measurements, and considered the form of sample to be taken from a population of Heterodera larvae which would give the most reliable estimate of the mean length of the whole population. Those studies were made on the larvae of H. rostochiensis only, but the ultimate purpose was to obtain strictly comparable estimates of the mean lengths of the larvae of all the known species of Heterodera in order to find out whether larvae of the different species could be identified by their length.

1. Observations on Fasciola hepatica in Limnaea truncatula under laboratory conditions showed that the cercariae did not emerge at temperatures below 9°C. Above 9°C. emergence proceeded indiscriminately up to the limit of experimental observation (26°C).

2. Experience showed that emergence occurred in the light or in darkness while changes in the hydrogen-ion concentration of the water containing the snails (within the range 5.5 to 8.5) had no effect on emergence. There was some evidence that an increase of carbondioxide in the water slowed but did not inhibit emergence but depletion of oxygen had no apparent effect.

3. In the laboratory, emergence could be induced by removing snails from dry habitats and immersing them in water or by removing snails from watery habitats and placing them in fresh water. We were unable to determine the exact physical.or chemical factors acting as a stimulus under such conditions.

Owing to the comparative rarity of Paramphistomes in Britain the difficulties of attempting to work out the life cycle are very great. Upto the present the problem has been approached from two angles; firstly, where an infected animal has been found at the abattoir, and finally traced back to its farm of origin, extensive collection of snails has been carried out at the assumed site of infestation ; secondly, where it has been possible to collect large numbers of adult worms from slaughtered animals, these have been picked out of the rumen and placed in dishes containing boiled tap water for several hours, in which medium oviposition takes place rapidly. These eggs have been collected and cultured, and laboratory-bred snails have been exposed to the miracidia, but so far no infection has taken place. This has of necessity been sporadic and no concentrated systematic attempts at infection over long periods have been possible.

1. Panagrellus silusiae was cultured in various media to determine the possibility of establishing it as a facultative parasite in the mammalian body. It was found to tolerate pH values of its environment between 1.0–8.5.

2. It survived for 24 hours in gastric juice but was rapidly killed by pancreatic juice. In both preparations larval mortality was higher than that of adults.

3. P. silusiae withstood environmental temperatures up to 87°C. At 40°C. death did not occur within 24 hours.

4. P. silusiae could survive without oxygen for at least 24 hours provided that the carbon-dioxide produced by its own respiration was not allowed to accumulate.

1. The lower intestinal tracts (duodenum to rectum) of 267 adult domestic fowls were examined for helminth parasites and 91% were found to be infested. The average numbers of worms and species present in infested birds were 240.6 and 2.42 respectively. Twelve species of parasites were recovered but only 5 occurred in more than 20% of the birds.

2. Twenty-six casualty and diseased chickens between 2 and 12 weeks old were examined. Fourteen were infested with helminth parasites and the average infestation was 499.9 worms of 2.79 species.

3. The total numbers of worms of all species present in individual fowls were shown to bear a relationship to the number of species comprising the infestations. Linear and quadratic equations which demonstrate the relationship have been derived from the observed figures.