653 
interpreting feeding experiments upon lower animals as applied to 
man, especially when we consider the great differences in suscepti- 
bility of the gastro-intestinal tracts of different species. This differ- 
ence is marked even among infants, for it is known that not all per- 
sons taking poisonous milk suffer equally, and some escape altogether. 
The “ endotoxines ” and bacterial proteids are substances which are 
more or less firmly retained by the living bacterial cells. The poison- 
ous action of these so-called “ toxines ” is closely associated with the 
phenomenon of anaphylaxis.® We are not yet sufficiently well ac- 
quainted with the composition and mode of action of this important 
class of poisons to formulate their relation to milk. 
The colon group. — The type of this large group of bacteria was 
first described by Escherich as Bacillus coli commune. While the 
colon bacillus is undoubtedly the cause of certain pyogenic and septi- 
cemic conditions, its power to produce harm in milk is uncertain. 
Normally it is practically always present in the lower intestines of 
mammalian animals, where it doubtless serves a useful purpose per- 
haps by keeping harmful varieties in check. * * * * 5 
The colon bacillus was at one time regarded as the common cause 
of various diarrheal infections, but it has now been differentiated into 
the dysentery bacillus, the typhoid bacillus, and other closely allied 
species. Even now it is difficult to disassociate its action from that of 
its closely allied cousin, the B. lacticus aerogenes. These two organ- 
isms sometimes induce excessive fermentation of lactose and other 
sugars with the production of irritating acids (especially acetic and 
lactic) and at the same time liberate an excessive amount of gas, 
thereby causing diarrhea. 
The typhoid bacillus. — It is known that this bacillus often con- 
taminates milk, which thus becomes the vehicle of some of the typhoid 
fever in large cities. The paratyphoid and paracolon organisms are 
closely allied and may doubtless be transmitted in like manner. The 
paratyphoid bacillus is a frequent cause of meat poisoning, but a 
similar action in milk has not been shown. 
° Rosenau, M. J., and Anderson, John F. : “ A study of the cause of sudden 
death following the injection of horse serum.” Bull. No. 29 Hyg. Lab., U. S. 
Pub, Health and Mar. Hosp. Serv., Washington, 1906. 
Rosenau, M. J., and Anderson, John F. : “Further studies upon hypersuscepti- 
bility and immunity.” Bull. No. 36 Hyg. Lab., U. S. Pub. Health and Mar. 
Hosp. Serv., Washington, 1907. 
Also Hyg. Lab. Bulls. Nos. 45 and 50, upon the same subject. 
5 For a full discussion of intestinal bacteria and their products, see Herter’s 
admirable book on the Common Bacterial Infections of the Digestive Tract and 
the Intoxications Arising from Them, 360 pages. New York, 1907. 
