134 MILK BACTERIA AND HEALTH. 



the bacteria that are present are of the normal, harmless, 

 lactic type. 



What kind of bacteria are associated with these digestive 

 troubles? As already stated, this question cannot yet be 

 positively answered. It has recently been alleged that the 

 cause of the common form of summer complaint in infants is 

 a bacillus called B. dysenteries (Shiga), which is also the 

 cause of certain forms of dysentery. This organism has been 

 found in a large number of cases of summer complaint and 

 may be their exciting cause. The organism in question is 

 one closely related to the cause of typhoid fever; it is not 

 easily distinguished from this latter bacillus and, therefore, 

 not easily separated from B. coli. This organism belongs to 

 the second of our groups of lactic bacteria, described on 

 page 69. Whether this bacillus is really the cause of such 

 troubles is not yet proved, and the source of the organism 

 in nature is as yet unknown, though it is possibly derived 

 from the water. Further evidence is needed before it can 

 be determined whether this organism is really the cause of 

 summer complaint. 



It is probable, moreover, that another class of bacteria, 

 those that we have referred to as the putrefying or pep- 

 tonizing bacteria, may have some close relation to this same 

 general class of troubles. Digestive disturbances are prac- 

 tically always accompanied by some form of putrefaction. 

 Inasmuch as the intestinal contents in these diarrheal 

 troubles almost always undergo putrefaction, it is quite 

 probable that putrefactive bacteria must have something to 

 do with the phenomena. Such changes in the contents of 

 the intestine must be attributed to putrefactive bacteria. 

 Moreover, it is well known that putrefaction is commonly 

 accompanied by the formation of toxic products. The de- 

 composition of albuminoids, taking place in the absence of 

 oxygen, gives rise to a large variety of decomposition prod- 

 ucts of more or less high chemical complexity. Among 



