^{page 152 note 1} This Journal, 1909, 3, 111—144.Google Scholar

^{page 153 note 1} This Journal, 1912, 5, 27, 86.Google Scholar

^{page 156 note 1} It seems impossible to convince some soil biologists that the organic matter of the soil suffers decomposition on heating to high temperatures, thereby changing the soil as a medium for the growth of organisms. Again and again we find distinguished investigators steaming soil under pressure and assuming that it has undergone no change. Conclusions drawn from experiments with these steamed soils are applied to ordinary unheated soils, not only without modification, but apparently without seeing the need for any modification. And yet for the past thirty years chemists have been giving proofs of this decomposition.

^{page 161 note 1} Hiltner, L. and Störmer, Studien über die Bacterienflora des Ackerbodens, mit besonderer Berücksichtigung ihres Verhaltens nach einer Behandlung mit Schwefelkohlenstoff und nach Brache, Arb. Biolog. Abt. Land- u. Forstwirtschaft. Kais. Gesund. 1903, Bd. 3, Heft 5.Google Scholar

^{page 161 note 2} Dicdrich Engberding, Vergleichende Untersuchungen über die Bakterienzahl im Ackerboden in ihnen Abhängigkeit von äusseren Einflüssen, Centr. Bakt. Par.. II, 1909, 23, 569–642.Google Scholar

^{page 162 note 1} Conn, H. J.Bacteria in Frozen soil, Centr. Bakt. Par. II, 1910, 28, 422–434.Google Scholar

^{page 162 note 2} Löhnis, F. and Sabaschnikoff, A., Ueber die Zersetzung von Kalkstickstoff und Stickstoffkalk, Centr. Bakt. Par. II, 1908, 20, 322–332. Other cases are quoted in Löhnis, Handbuch der Landw. Bakterologie, 1910, p. 596.Google Scholar

^{page 170 note 1} The only case of this action we have observed. See footnote, p. 215.

^{page 172 note 1} Russell, E. J. and Petherbridge, F. R.this Journal, 1912, 5, 106.Google Scholar

^{page 172 note 2} Loc. cit. p. 110.

^{page 184 note 1} Transactions of the Linnean Society of New South Wales, Nov. 30th 1910.

^{page 184 note 2} Report of the British Association, 1911.

^{page 184 note 3} It might arise from a difference in the amount of calcium carbonate present.

^{page 185 note 1} This slow growth of the destructive organisms, which was emphasised in our earlier paper, vitiates some of the criticisms that have been passed on our conclusions. For example, Lipman, Blair, Owen and McLean (Experiments relating to the possible influence of protozoa on ammonification in the soil, New Jersey Expt. Station Bull. 248, 1912) added pasteurised and untreated soil infusions respectively to mixtures of sterilised soil (heated under a pressure of 1.5 atmospheres of steam) and dried blood. After seven days the pasteurised infusion had induced the formation of no more ammonia than the untreated infusion. They conclude that these results “do not bear out Russell and Hutchinson's contention as to the part played by protozoa in depressing the activities of soil bacteria.”

It does not appear to us that the experiment really bears on the subject. In no case have we observed development of the destructive organisms in anything like so short a time as seven days. Two assumptions are also involved which the facts do not warrant: (1) the amount of ammonia formed is taken as a measure of the number of bacteria (see pp. 191 et seq. on this point), (2) subjecting the soil to the high temperature of steam at 1½ atmos. is supposed to leave it unchanged. The argument as we understand it reduces itself to this: the destructive organisms made no growth in seven days in a medium A (strongly heated soil), therefore they could make no growth in a longer period in a wholly different medium B (ordinary unheated soil).

In common with other soil investigators Fred (über die Beschleunigung der Lebenstätigkeit höherer und niederer Pfanzen durch kleine Giftmengen, Centr. Bakt. Par. 1912, II, 31, 185—245) assumes that heating the soil has no effect except to kill micro-organisms. He heated soil to 100°C, added ammonium sulphate and then ether, and continues “nach Russell und Hutchinson's ansicht würde dieses Antiseptikum in amöbenfreiem Boden dann keine günstige Wirkung haben” (we expressly stated in our earlier paper that we made no such claim; see also p. 156 here). No favourable action was observed, as a matter of fact, excepting only when untreated soils were treated with ether and the author admits that “Diese Beobachtung spricht fur Eussell und Hutchinson, doch” —he naïvely continues— “doch ist es möglich, und sogar wahrscheinlich, dass die gesteigerte Nitrifikation durch Äther auf einer Reizwirkung auf die nitrifizierenden Bakterien selbst beruht.”

^{page 186 note 1} This aspect is discussed in this Journal, 1912, 5, 27, 86.Google Scholar

^{page 186 note 2} A contribution to our knowledge of the protozoa of the soil. Proc. Roy. Soc. 1911, 84 B 165—180.CrossRefGoogle Scholar

^{page 186 note 3} A note on the protozoa from sick soils; ibid.. 1912, 85 B, 393—400.

^{page 186 note 4} Ueber neue Ergebnisse und Probleme auf dem Gebiete der landwirtschaftlichen Bakteriologie, Jahresber. Verein für Angew. Botanik, 1907, 5, 200.Google Scholar

^{page 186 note 5} Die Wirkung des Schwefelkohlenstoffs auf dem Boden, ibid. p. 123.

^{page 186 note 6} Der Einfluss der Bewässerung auf die Fauna der Ackerkrume mit besonderer Berück sichtigung der Bodenprotozoen, Mitt. Kaiser Wilhelm Instit. für Landw., Bromberg, 1909, 1, 382–401;Google ScholarUeber Bodenprotozoen, Centr. Bäht. Par. 1912, II, 33, 314—320.Google Scholar

^{page 186 note 7} Studien über edaphische Organismen, Centr. Bakt. Par. 1912, II, 32, 1—7.Google Scholar

^{page 186 note 8} Some Bio-chemical investigations of Hawaiian Soils, Bull. 34, Expt. Station of the Hawaiian Sugar Planters' Association, 1910.

^{page 186 note 9} Annual Report of the Porto Rico Agricultural Expt. Station, 1910. Also Emmerich, R., zu Leiningen, W. Graf u. Loew, O., Über Bodensaiiberüng, Centr. Bakt. Par. 1912, II, 31, 466—477. Other references are given in Goodey'a paper (loc. cit.).Google Scholar

^{page 187 note 1} Methode zur Schätzung der Anzahl von Protozoën im Boden. Centr. Bakt. Par. 1913, II, 36, 419–421.Google Scholar

^{page 190 note 1} See Russell and Petherbridge, this Journal, 1912, 5, 107.Google Scholar

^{page 191 note 1} See footnotes to Tables V and VI (pp. 168 and 169).

^{page 197 note 1} We attribute it to loss of ammonia by volatilisation because we only get it where much ammonia is present and where there has been a distinct loss of water by volatilisation. Thus in the present instance the toluened soil and the toluened soil+ammonium sulphate contained initially 41.5% and 43.6% of water, whilst at the end they contained 37.4% and 35.2%, losses of 4.1% and 8.4% respectively. The amounts of ammonia present reached the unusually high figures of 134 and 277 parts per million (nitrification being considerably retarded) and the falling off from the usual straight line on the curve (i.e. the amount we suppose to be lost) to 37 and 49 parts per million.

^{page 197 note 1} Annales Agronomique, 1896, 22, 449. Bréal had observed that the production of ammonia went on when the nitrification was suspended by treatment with antiseptics, but soon came to an end. He explained this by assuming assimilationGoogle Scholar.

^{page 209 note 1} We have shown in our previous paper that the amount of unstable intermediate products as well as of ammonia is increased by partial sterilisation.

^{page 209 note 2} E.g. this Journal, 1912, 5, 98.Google Scholar

^{page 211 note 1} It will be noticed that ammonia accumulates in the soils maintained at 40° and over, showing that the nitrifying organisms no longer work much, if at all.

^{page 215 note 1} In the course of four years we have only found one exception. The results obtained at 30°, 40° and 50° are expressly excluded here.