TRICHOMONAS HOMINIS: DIET 



ture is a factor that can be disposed of at once since it 

 does not change much even in patients suffering" from 

 diseases accompanied by fever, and culture experiments 

 have shown that the organisms are able to Hve and repro- 

 duce within a wide temperature range. The normal tem- 

 perature of man is evidently favorable. The digestive 

 juices also probably play a minor role. The degree of 

 moisture is no doubt a more important factor since the 

 density of the intestinal contents must affect the activities 

 of the flagellates. 



Diet. Perhaps the character of the food of the host 

 has the greatest influence on the flagellates since diet 

 determines to a considerable extent the character of the 

 bacteria and the products of bacterial decomposition 

 within the large intestine. There seems to be a definite 

 relation between the presence or absence of intestinal 

 protozoa and the character of the diet, whether herbiv- 

 orous or carnivorous. A survey of the literature avail- 

 able (Hegner, 1924b) indicates that intestinal protozoa 

 are rare in strictly carnivorous mammals, less rare in 

 omnivorous mammals, but common in herbivorous 

 species. Feeding experiments with rats (Hegner, 1923a) 

 show a carnivorous diet to be unfavorable for intestinal 

 flagellates. When laboratory rats infected with tricho- 

 monads were fed for one week on a carnivorous diet 

 that was favorable for the growth and reproduction of 

 the rats, the number of trichomonads decreased to less 

 than one-fiftieth of the number present in control rats. 

 Changes in the hydrogen-ion concentration of the intes- 

 tinal contents do not account for this loss (Hegner and 

 Andrews, 1925), but the conclusion was reached that the 



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