702 ARTHUR ISAAC KENDALL 



coli and related forms as the more common organisms which produce 

 indol in the alimentary canal. 



From what has been stated above, the increase in carbohydrate and 

 a restriction of the protein in the diet tend of themselves to change the na- 

 ture of the products formed by colon and other bacilli from the indolic to 

 the lactic type. If enough carbohydrate can be ingested to maintain a car- 

 bohydrate content throughout that portion cf the tract where bacterial pro- 

 teolysis is dominant, the substitution of lactic acid for products of' protein 

 putrefaction through the shifting of the metabolism of the facultative 

 bacteria, as Bacillus coli, naturally follows. The success of the dietary 

 change will depend in no small degree upon the extent to which carbo- 

 hydrate may be kept continuously in the alimentary canal. In general, 

 therefore, it may be stated that the chief beneficial results observed 

 in cases of so-called intestinal auto-intoxication which have been dieted 

 upon Bulgarian lactic acid milk are to be ascribed largely to the restriction 

 of the protein, and to an increase in the carbohydrate. 



This leads to a diminution of the protein residuum in the intestine, to 

 the shifting of the metabolism of the intestinal putrefactive bacteria, and to 

 lactic acid production in- place of indologenesis. The increase of peristal- 

 sis, and partial or complete relief from constipation, which not infre- 

 quently follows the change from a basic to an acidic reaction in the middle 

 segment of the alimentary tract, may also be a factor in the beneficial 

 process. 



Since the publication of Metchnikoff's work, many attempts have been 

 made to secure cultures of lactic acid bacilli for purposes of lactic acid 

 implantation. None of these to date are selected with a view to their 

 fitness for intestinal acclimatization. The efforts have been to seek for 

 milk parasites, which will produce a smooth, palatable and very acid 

 sour milk outside the human body. Some cultures have even been dis- 

 pensed as tablets or lozenges. The bacteria in such preparations are 

 dried, much like commercial yeast cakes, and are to be taken in this form. 

 Frequently, the directions for using these dried cultures of bacteria fail 

 to indicate that sugar be taken with the bacterial tablets. It must be 

 obvious that these bacteria, or almost any other bacteria, cannot be ex- 

 pected to produce therapeutic amounts of lactic acid unless they are pro- 

 vided with a source of energy from which lactic acid may be formed. 



If, therefore, intestinal implantation of normal lactic acid bacilli is 

 to be practiced, it would appear logical to select normal intestinal lactic 

 acid bacilli for inoculation into milk, intended for therapeutic purposes, 

 or for ingestion as pure cultures, and to maintain these cultures under 

 conditions which shall guarantee they have not lost their intestinal para- 

 sitism in favor of parasitism upon artificial media outside the body (Rotch 

 and Kendall). It is not improbable that frequent passage of such cul- 

 tures through the alimentary canal will be found essential to maintain 



