22 HUMAN AND ANIMAL WASTES 



mastric and Trichomonas^ capable of living and even of multiplying 

 in excreta. The coprophilic protozoa comprise various flagellates, cer- 

 tain amebae, and ciliates. The liquid part of the manure is considerably 

 richer than the solid in total number of protozoa as well as in species, 

 including Polytofna uvellay Cryftochilum nigricans^ and T etramUus 

 rostratus. These protozoa nearly all feed upon bacteria. The infusoria 

 may feed upon smaller protozoa, so that forms like Colpdium may not 

 destroy bacteria at all. 



Human and animal excreta also contain a large population of fungi, 

 chiefly in a spore state. Schmidt (837) divided the manure-inhabiting 

 fungi into three groups : 



Those found only in manure ; their spores are swallowed with the feed, 

 and they pass unchanged through the digestive tract, though they 

 are favorably influenced toward germination by the body heat and 

 digestive fluids of the animal. Their natural multiplication by spores 

 is impossible without the physiological action of the digestive proc- 

 esses. 



Those that do not have to pass through the digestive tract of an animal in 

 order to germinate and develop. The representatives of this group 

 occur in nature only in manure, although some are able to grow also 

 on other substrates. They can be cultivated both on manure and on 

 other media, mostly at ordinary temperatures. 



Organisms found both in manure and on other substrates. They grow 

 readily at room temperature on a number of media. 



Comfosition and Decomposition 



The chemical composition of human and animal excreta, and of 

 stable manures in general, varies considerably, depending on the nature 

 of the animal, its age, mode of nutrition, and composition of food- 

 stuffs (463). As soon as voided, manure begins to undergo rapid de- 

 composition. This results in the formation of ammonia and various 

 other nitrogenous degradation products. These give rise to offensive 

 sm.ells, which are controlled by the conditions of decomposition. From 

 a sanitary point of view, it is essential that decomposition should be 

 accompanied by the destruction of the injurious organisms present in 

 the manure. The fecal organisms gradually disappear and their place 



