6 
study of the subject are referred to the treatise of Rettger and 
Cheplin (74) and to Kopeloff's book entitled "Lactobacillus 
Acidophilus" (SI). 
To summarize, it is generally accepted that L. bulgancus can 
seldom, if ever, be implanted in the intestinal tract. The beneficial 
results ascribed to L. bulgaricus milk might well be due to the milk 
sugar, of which normal cows' milk contains about 5 per cent. On 
the other hand, L. acidophilus is a normal inhabitant of the intestinal 
tract and under the influence of the ingestion of lactose or dextrin can 
be made to predominate the intestinal flora. The ingestion of L. 
acidophilus milk, with or without added lactose, brings about the 
transformation of the intestinal flora more quickly and is generally 
conceded to be the most logical and practical method of bringing 
about the preponderance of the L. acidophilus type of bacteria in the 
intestines. By administering L. acidophilus milk implantation and 
proliferation of the organisms in the intestinal tract are most rapidly 
accomplished, for then there is direct implantation of large numbers 
of viable organisms. The lactose of the milk induces the multiplica- 
tion of the desired type of bacteria. 
FOOD VALUE OF FERMENTED MILKS 
The high food value of milk is too generally recognized to need 
discussion here; fermented milks also have a high food value, except 
that in some cases the fat is partially or entirely removed. Other- 
wise the food value of the fermented milk differs little from that of 
the fresh milk from which it is made. Any increased digestibility 
of the fermented milk is due not so much to change in the chemical 
nature as to the fact that the casein is furnished in a precipitated 
and finely divided condition. In none of the fermented milks is there 
any material cleavage of the casein resembling the digestion in the 
stomach. The fat is practically unchanged, and only a part of the 
sugar is converted into acid, alcohol, or gas. In certain gastric 
troubles in which it is difficult to find any food that can be retained 
by the patient, fermented milks are frequently used with good results. 
Kefir and kumiss especially are used under such circumstances, as 
the stimulating action of the carbon dioxide which they contain is 
believed to aid in their digestion. To the physician the value of a 
highly nutritious food which can be digested when other foods are 
rejected is obvious. 
Many questions should be very carefully considered before a 
fermented milk is introduced as an important part of the diet. As 
Herter (44-) has pointed out in the paper already cited, the addition 
of fermented milk to the diet may change very materially the ratio 
of protein to other classes of food. If the milk is taken in place 
of other food, the daily protein ration may be so reduced that in- 
testinal putrefaction, which is dependent on the protein part of the 
food, is diminished. On the other hand, if milk is added to the usual 
food, the protein ration may be increased rather than diminished. In 
many cases the condition of the mucous membranes will not permit 
the presence of organic acid, and sour milk can not be retained. It 
is also possible that symptoms of autointoxication are not caused by 
unusual bacterial activity in the intestine but by functional failure of 
