ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
653 
but is in some way dependent upon their albuminoid constituents. It 
would furthermore appear that this singular and apparently most 
significant capacity of the body fluids is ultimately associated with that 
complex condition which we call life.” 
In conclusion, we may state that the author’s paper is a most 
excellent summary of the present condition of this question, as well as 
a record of his own personal experience. 
Bacteria of Milk.* — Professor H. W. Conn, in discussing the bac- 
teria of milk, remarks that their function varies with the species, some 
of them having the property of imparting an agreeable flavour to the 
butter made from it, while others communicate a disagreeable odour 
and taste. 
From milk and cream the author has isolated 40 different species, 
which, from their effects, are divisible into three classes : — (1) Some 
produce no visible effect, the milk remaining apparently unchanged. 
Some of these, however, render it slightly acid, others slightly alkaline, 
and nearly all produce certain decomposition odours. (2) Another 
series has the power of breaking up the milk-sugar, producing sufficient 
acid to curdle the milk. To this belongs B. acidi lactici. (3) A third 
class curdles milk, but the reaction is either alkaline, or the reaction is 
not affected. Such bacteria have the additional function of dissolving 
the curd which they produce, converting it slowly into peptones, whereby 
the milk becomes liquid again. 
The author then proceeds to discuss the connection between butter 
and bacteria, the connection being established through cream, in which 
the growth is longer continued and more prolific. Now the action of 
bacteria on cream results in what is known as “ ripening,” by which 
butter “ comes ” more easily ; secondly, it keeps longer ; thirdly, the 
flavour is improved. 
The ripening is effected by the action of bacteria which disintegrate 
the albumen, partly by production of an acid, and partly by a 
peptonization. The flavour is due to the impregnation of the butter 
with aromatic principles, the product of decomposition ; the differ- 
ence in taste and odour being due to the action of different bacterial 
ferments. Hence butter made from sweet cream is flat, insipid, and 
tasteless, because the bacteria have not had time or opportunity to 
produce the volatile decomposition products. 
The author finally discusses the relation of milk-souring to elec- 
tricity. From a series of experiments made on milk, he finds that 
electricity has not this effect on milk, and offers in explanation that 
“ thunderstorms are usually preceded by climatic conditions of tempera- 
ture and moisture very favourable to bacteria growth.” 
Spirobacillus gigas.f — M. A. Certes has found in the freshwater 
reservoirs at Aden a Spirillum which is remarkable in form and size. 
In length it varies from 15-35 /x, and the width of the spirals is 
from 7-8 /x. In breadth the Spirillum does not exceed 1 /x. When 
alive or fixed by osmic acid, it resembles a spiral spring made of glass, 
* ‘ Associated Dairying. Connecticut Board of Agriculture ; Report,’ 1890, 
43 pp. 
t Bull. Soc. Zool, France, xiv. (1889) pp. 322-5 (8 figs.). 
