EXCRETIONS 505 



per cent Gram positive and 2.3 per cent free spores. Mattill and Hawk(a), 

 who employed the MacNeal method slightly modified (no ether extrac- 

 tion used), obtained slightly higher results on two subjects who were 

 followed for several weeks. They found that the bacterial nitrogen aver- 

 aged 53.9 per cent of the fecal nitrogen and the bacterial dry substance 

 8.27 grams. Tinder normal conditions the bacteria probably derive their 

 sustenance in considerable part from the intestinal secretions and excre- 

 tions, but pathologically they may decompose appreciable amounts of par- 

 tially digested protein and carbohydrate. 



In nurslings the bacterial flora is relatively simple, though later in 

 life the number of these bacterial forms becomes very large. The dominant 

 organism in nurslings is B. bifidus (B. acidophilus of Moro is also 

 present), but this is ultimately replaced by B. coli and B. ladis 

 acrogenes. Other organisms which may be observed are coccal forms, 

 B. welchii, and in certain cases, B. putrificus (Herter(d)). These last two 

 organisms Herter is inclined to associate with conditions of excessive putre- 

 faction in the intestines. MacNeal has pointed out, however, that B. 

 welchii can generally be detected in normal stools. In early life the prod- 

 ucts of intestinal decomposition are very small in amount, and, as would 

 be expected, the number of putrefactive bacteria are few. One finds, 

 however, in middle life a large number of persons in whom the putre- 

 factive conditions in the intestine are distinctly more active than was the 

 case earlier in life. Apparently the most important factors in bringing 

 about this strongly proteolyzing type of bacterial flora are the consumption 

 of an overabundance of protein food, combined with inadequacy in the 

 digestive juices, delayed absorption, and insufficient motility in the ali- 

 mentary canal. Very little decomposition takes place in the large intes- 

 tines under the action of B. coli, however, if the absorption in the small 

 intestine has been good. Rettger and his coworkers have recently pointed 

 out that the daily administration of 150-300 grams of lactose or dextrin 

 to adults will, with few exceptions, bring about a marked change in the 

 bacterial flora in which the usual mixed types of bacteria give way to 

 B. acidophilus, which is a normal intestinal organism, but which is pres- 

 ent in the intestine after early infancy in relatively small numbers only. 

 This method would appear to possess interesting possibilities of thera- 

 peutic usefulness. 



Amount. Upon the ordinary mixed diet, the daily fecal excretion of 

 the adult, male averages from 100 to 150 grams, with a solid content vary- 

 ing between 20 and 40 grams. Upon a vegetable diet the fecal output 

 will be much greater, reaching 350 grams with a solid content of 75 

 grams, and even more. This being the case, data on variations in the 

 daily excretion are of little practical significance, except where the com- 

 position of the diet is accurately known. Lesions of the digestive tract, 

 a defective absorptive function, or increased peristalsis, as well as admix- 



