655 
associated with streptococcic infections and are probably dependent 
upon them. 
The Streptococcus lactis , first described by Kruse, has been proved 
by Heinemann in this country to be one of the common causes of 
lactic acid fermentation in milk. It appears to be indistinguishable 
from the pathogenic forms and is always present in market milk. 
The anaerohic spore-bearing micro-organisms. — Fliigge first 
pointed out the importance of the anaerobic spore-bearing organisms 
in milk and their relation to infantile diarrheas. He especially 
singled out the B. butyricus (Botkin). It now appears that Botkin’s 
bacillus represents two distinct micro-organisms. Herter considers 
that the B. putrificus and the B. aerogenes capsulatus , which grow in 
milk, play an important role in intestinal putrefaction. The B. 
aerogenes capsulatus , for instance, produces poisons belonging to 
the hemolytic and proteotytic class. According to Kamen,® it also 
forms soluble poisons obtainable by filtration. Kamen likens this 
poison to “ sepsin,” in that it acts as a respiratory poison and induces 
vomiting, diarrhea, tenesmus, and death. This poison is not de- 
stroyed by heating to 60 ° for fifteen minutes. 
In addition to the bacteria and the bacterial products above con- 
sidered, the products of fermentation and putrefaction in milk have 
long been regarded as poisonous substances. Just which of these 
products are the chief culprits is far from being determined, although 
much work has been done upon the subject. The best known prod- 
ucts of fermentation and putrefaction are the following: 
Acids . — Milk frequently contains lactic, butyric, acetic, and other 
organic acids, which result from the common fermentative changes. 
The higher volatile fatty acids come especially from the spore-bear- 
ing anaerobes, and result from putrefactive decomposition in the 
milk. All these acids are irritants, by virtue of their acid properties. 
If present in considerable concentration in a healthy digestive tract 
or in a more moderate concentration in a person with an irritable 
stomach or with deranged digestion they may be factors in exciting 
vomiting or diarrhea. It is probable that when these acids produce 
acute symptoms they result more from fermentative processes within 
the gastro-intestinal tract rather than from those produced in milk 
before it is taken. 
The presence of excessive amounts of acids in the intestinal tract 
may indirectly produce chronic poisonous conditions by robbing the 
organism of alkali. 
Basic substances . — The true bacterial toxines were first thought by 
chemists to be basic substances resembling alkaloids. We now know 
« Kamen: Zur Etiologie der -Gaspklegmone. Cent. f. Bakt., Orig., vol. 35, 
1904, pp. 555, 686. 
