186 



various products might be of a toxic cliaracter, and also highly probable that if 

 these yeasts were growing vigorously and metabolic activity high, these toxic sub- 

 stances might cause injurious effects either locally or constitutionally in the ani- 

 mal body. 



A somewhat common opinion in regard to the yeasts is that when taken into 

 the stomach in bread not cooked sufficiently they set up a fermentation, generate 

 gas, and thus cause great discomfort, though the same kind of gas when taken in 

 soda water seems to have a rather soothing effect. Then this opinion does not 

 seem to prevail in regard to the use of beer or other fermented drinks, though 

 there is no question in regard to the presence or vitality of the yeasts in these 

 beverages. 



To determine the effect of yeasts taken into the stomach, two rabbits were 

 placed in a cage in the laboratory where they could be observed conveniently. 

 They were kept over night without any food, and in the morning were given two 

 compressed yeast cakes. These they refused to eat, presumably from their be- 

 haviour objecting to the odor. The yeast was then smeared on sugar beet, which 

 they ate. No apparent result followed. After two days about two grams of a 

 pure culture yeast were smeared on sugar beet, which was fed them, after which 

 a week was allowed to intervene. Then, at intervals of two days, each rabbit was 

 given a dry yeast cake, until each one had eaten five cakes. The dry cakes were 

 eaten with avidity, being preferred to the sugar beets, their usual food. At the 

 end of this treatment the rabbits were still healthy, had apparently experienced 

 no discomfort from the unusual addition to their diet, and showed no symptoms 

 of disease. After two days one was chloroformed and then examined, to deter- 

 mine if there were any internal lesions. There proved to be none, all the organs 

 being in their normal, healthy condition. During this examination inoculations 

 were made from the various parts of the intestinal tract — cardiac portion of 

 stomach, pyloric portion of stomach, duodenum, jejunum, ileum, caecum, anterior 

 colon, posterior colon — into sterilized bouillon and wort. 



During the time the experiment was in progress, inoculations were made 

 daily into sterilized bouillon and wort from the discarded portionsof food which had 

 passed through the intestinal tract. Out of those cultures in wort seven developed 

 yeast alone, seven developed yeast and mould, and two developed mould alone. In 

 conjunction with two of the yeasts was a red yeast which occurs in the air in the 

 laboratory. All of the cultures in bouillon, but one, had a bacterium, resem- 

 bling the " thrix " forms. An inoculation into bouillon and wort was made in 

 each case from the same material, the bouillon being neutral, the wort acid. 

 The yeasts and mould developed in the wort, but not in the bouillon, whereas, 



