372 
new supplies of the kefir grains obtained. Struve (33) gives the fol- 
lowing proximate chemical analysis of kefir grains dried at 100° C. : 
Per cent. I 
Water 11. 21 
Fat 3. 99 
Soluble peptone-like substances 10. 98 p 
Proteids soluble in ammonia 10. 32 
Proteids soluble in caustic potash 30. 39 j 
Insoluble residue 33. 11 j 
100. 00 I 
The whole of the active matter of the ferment was contained in | 
the insoluble residue. A microscopic examination of this showed it I 
to consist of a mixture of yeast cells with Bacterium dispora Cau- \ 
casica (Kern). In a few specimens leptothrix and oidium lactis were 
also present. According to this author, the yeast cells, which have , 
been somewhat modified by their growth in leather bottles, are alone 
responsible for the peculiar kefir fermentation. i 
According to Vieth (34) milk sugar ordinarily does not readily j 
undergo alcoholic fermentation with yeast. With kefir grains, how- i 
ever, a rapid alcoholic and lactic fermentation takes place. Accord- 
ing to this author also the ferment of the grains consists of the | 
Bacillus dispora Caucasica (Kern) and a modified form of the ordi- 
nary yeast, Saccharomyces cerevisice. According to von Freudenreich 
(35) the grains contain at least two species of bacteria and one species | 
of yeast, which acting together produce the kefir fermentation. The 
bacteria effect the inversion of the milk sugar, after which a portion 
of the simpler sugar is converted into alcohol by the action of the j 
yeast and another portion into lactic acid by the further action of the I 
bacteria. The milk is curdled during this fermentation. * 
According to Martinand (36) milk undergoes alcoholic fermenta- ] 
tion with a great many species of yeasts, especially if glucose and | 
maltose be added, and coagulation of the milk occurs under these j 
conditions even in the absence of acid. 
Part II. — (4b) Milk Poisoning — Galactotoxismus. 
Of all foods milk is probably the most subject to contamination 
and change. Of the various forms of contamination to which it is 
liable the commonest is, as we have already seen, that which results 
from the introduction into the milk of lactic-acid-producing bac- 
teria from various sources. These organisms accomplish those 
changes which are familiar to us in the ordinary souring of milk. 
IWiile according to Stoakley (1) buttermilk is sometimes responsi- 
ble for acute milk poisoning, it is the general opinion that sour 
milk but rarely gives rise to troubles of this character. Indeed, by 
a number of medical authorities sour milk is regarded as a very 
