ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 833 



under artificial conditions binders the putrefaction which the lower 

 organisms occasion in nitrogenous fluids, and may even entirely stop 

 it. This appears to the author to account for the gradual subsidence 

 and ultimate complete disappearance of fevers and other ferment 

 diseases caused by them. In malaria, these organisms appear to lose 

 their infectious properties very rapidly, and thus become incapable 

 of conveying the malady from one infected animal nidus to another. 

 Under favourable conditions they may however return to the con- 

 dition of natural germs, and become once more infectious. In this 

 way malaria may be conveyed by human subjects from an infected 

 district to one previously free. The rapidity with which this re- 

 version of the germs to their natural condition takes place may be 

 the cause of the extreme contagiousness of such diseases as the 

 distemper of cattle. 



Prevention of Fermentation by Vegetable Acids.* — M. Marcken 

 gives the following as the proportions of various acids which prevent 

 a solution of sugar from fermenting : — acetic acid ■ 5 per cent. ; formic 

 acid 0*2, propionic acid 0*1, butyric acid 0'05 (or completely when 

 • 1 per cent, is present), and a mere trace of caj>ronic acid. A propor- 

 tion of 0*6 per cent, of acetic or ■ 05 per cent, of butyric acid in a 

 nutrient fluid prevents the increase of yeast ; while as much as 3 • 5 

 per cent, of lactic acid is required for the same purpose. 



Fermentation of Maize-starch.t — V. Marcano has investigated 

 the process of fermentation in " chicha," an alcoholic liquid pre- 

 pared by the American Indians from maize-grains. He states the 

 fermentation to be due to the reproduction of a very characteristic 

 organism, which has three forms of development, as a vibrio as 

 nucleated torula-like globules, and as myceloid tubes, from which 

 at a certain period, vibrios escape, the membi-ane which forms the 

 septa of the filament being at the same time resorbed. It is found in 

 the exterior pellicle of maize-grains, and can be transformed from one 

 form into another by culture in different nutrient fluids. 



The ferment of chicba is further characterized by the property of 

 acting directly on young starch, such as that contained in the embryo 

 of maize-grains ; the products of decomposition being dextrin, alcohol, 

 and carbonic acid gas. The starch-grains on which it has acted are 

 reduced to the condition of flakes of cellulose-starch (farinose), all the 

 granulose having disappeared. 



The organism resists the action of boiling water at 95° C. con- 

 tinued for some minutes ; the most favourable temperature for its 

 production being 40°-45°. It can also ferment milk-sugar, saccharose 

 and glucose. During the germination of maize, the vibrios develope 

 in the interior of the grain in vast numbers. They have also been 

 detected in the stem, immediately beneath the bark, and in the 

 leaves. 



The facts here recorded are considered by the author to explain the 



* Zeitschr. f. Spiritusindustrie, iv. (1881) p. 114. See Bot. Centralbl xi 

 (1882) p. 299. ■ '' ' 



t Coniptes Kcndus, xcv. (1882) pp. 315-7. 



