30 HARRY WARREN ANDERSON 



Mycoderma species studied. Many of the red yeasts from the intestinal tract 

 were indistinguishable from Saccharomyces glutinis and Torula rubra in gross 

 characters. However, it was not possible to demonstrate that any of the species 

 isolated were identical with Saccharomyces cerevisiae, S. ellipsoideus, and other 

 culture yeasts. Several of the isolated species, for example, 152 and 158.3, were 

 very similar in their biochemical properties to Monilia Candida. 



A number of wild yeasts were also isolated from the air and from decaying 

 fruits and vegetables. These were even more closely related to the intestinal 

 organisms than were the nonpathogenic yeasts listed in the table. In the light 

 of the feeding experiments described later, it is certain that these yeasts, when 

 ingested with the food, will pass through the alimentary tract in a living con- 

 dition and may be isolated from the feces. It is probable, therefore, that the 

 majority of the yeasts isolated in this investigation are these wild species so 

 common in nature. That there is no one yeast species common to the intestinal 

 tract of man is demonstrated by the fact that the majority of the numerous 

 cultures isolated showed, from even a superficial study, that they were of 

 distinct species. It is interesting to know, in this connection, that Saccharo- 

 mycopsis guttulatus is constantly found in the intestinal tract of rabbits. This 

 species was not met with in the course of the present investigation, and is 

 certainly not common in the intestinal tract of man. 



FEEDING EXPERIMENTS WITH YEASTS 



The most exhaustive feeding experiments with yeasts were those 

 carried out by Neumayer ('91) referred to in a previous section. In 

 these experiments, however, the investigator used only a few species 

 of yeasts and these were, for the most part, the usual fermenting forms 

 of commerce. Neumayer proved that the various secretions encount- 

 ered throughout the alimentary tract were either favorable for the 

 development of the yeasts or neutral in their influence. Those secretions 

 which were harmful had little influence on account of the fact that the 

 yeast cells quickly passed beyond their influence, and the short period 

 during which the cells were in contact with them was not sufficient for 

 harmful action. He also observed that the yeasts found in the feces 

 were not in a budding condition and that many of them were dead. He 

 proved that, while the sum of the conditions in the digestive tract was 

 not favorable for development and multiplication of these fungi, they 

 still were able to survive in comparatively large numbers. The result 

 of his experiments shows that the ordinary fermenting yeasts and wild 

 yeasts found in beer and grape must are not harmful when fed alone, 

 but may cause serious illness when fed with fermentable carbohydrates. 



Few other investigators have attempted to prove the pathogenicity 

 of yeasts by feeding, seemingly preferring to inject the organism into 

 the blood stream or into the peritoneal cavity. Ashford ('16) has made 

 a complete series of experiments on laboratory animals with his sprue 

 organism. In his feeding experiments he found that the fungus is 



