ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 693 



Degeneration of Yeast.* — M. H. Bungener states that yeast which 

 has been repeatedly employed for fermenting purposes becomes after 

 several generations unfit for further use. This is apparently due to 

 diiferences in the composition of the wort, especially with reference 

 to its nitrogenous constituents. After each fermentation the quantity 

 of the nitrogen in the yeast increases, as does also its fermenting 

 power; but after a time the fermentation ceases, leaving the cells 

 Btill suspended in the liquid, and the yeast is no longer fit to use. 



Effect of High Pressures on the Vitality of Ferments and on 

 Fermentation. "j" — In continuation of previous experiments on the effect 

 of high pressures on low organisms by M. A, Certes,J MM. Certes 

 and D. Cochin state that the vitality of Torida is not destroyed by a 

 pressure of 300-400 atmospheres continued for several days. Exami- 

 nation under the Microscope shows no perceptible change in the form 

 or appearance of the cells ; and when afterwards brought into contact 

 with saccharine solutions, they multiply and otherwise behave in the 

 normal way. Under the same pressure alcoholic fermentation always 

 takes place after some time. "When fermentation occurs under high 

 pressures, the development of carbon dioxide appears to ensue under 

 special conditions of molecular equilibrium. 



Organisms Productive of Zymosis.§ — M. A. Bechamp, a projpos 

 of communications by MM. Duclaux and Pasteur,|| claims priority for 

 the discovery of the production of diastases by germs and the role of 

 these same germs in digestion. He cites passages from the ' Comptes 

 Eendus,' and states that it would be easy to prove by other quotations 

 from the same source that diastase, synaptase, the soluble ferment of 

 the pancreas, pepsine, &c., are equally products of the physiological 

 activity of microzoa, bacteria, or autonomous cells. 



Microbes in the Soil.t — Dr. E. Wollny states that the changes, 

 physical and chemical, which take place in earth containing humus, 

 or the organic remains from which it is formed, have important 

 bearings on the fertility of the soil. In well-worked porous and 

 aerated ground the decomposition of organic matter under favourable 

 conditions liberates carbon dioxide, water, ammonia, and a little free 

 nitrogen, some of which combine with the inorganic substances 

 necessary for the growth of the plant. In well-aerated soil little 

 ammonia is formed ; it is quickly oxidized to nitric acid. The agent 

 in this nitrification consists of small filiform bodies which are widely 

 diffused in arable soils, but apparently do not exist in the air. If this 

 organism is destroyed by treatment with chloroform or carbon bisul- 

 phide, or by heat, the ammonia remains or the nitrites and nitrates 

 are reduced. Heat greatly influences the growth of this ferment ; at 



• Bull. S<jc. Chim., xlii. pp. 567-73. See Journ. Chem. Soc. — Abstr., xlviii. 

 (ISS-v) p. 417. 



t Bui). Ara.l. II. Bclg., viii. (1884) pp. C52-4. 



X Hoc thirf .JouiDal, iv. (1884) p. 8U7. 



§ ConiptcH I'lOiidus, c. (1885) pp. 458-61. 



[I See thiM Journal, ante, p. 'i!)5. 



•j Bifcd. Cfcnt., 1884, pp. 700-814. See Journ. Chem. Soe,— Abstr., xlviii. 

 (1885) p. 426. 



Ser. 2.— Vol. V. 2 Z 



