34 PROTOZOOLOGY 



possess extraordinary capacity to adapt themselves to an entirely 

 different environment. For example, Dobell (1918) observed in the 

 tadpole gut, a typical free-living limax amoeba, with characteristic 

 nucleus, contractile vacuoles, etc., which was found in numbers in 

 the water containing the faecal matter of the tadpole. Glaucoma 

 (Tetrahymena) pyriformis, a free-living ciliate, was found to occur 

 in the body cavity of the larvae of Theobaldia annulata (after 

 MacArthur) and in the larvae of Chironomus plumosus (after Treil- 

 lard and Lwoff). Lwoff successfully inoculated this ciliate into the 

 larvae of Galleria mellonella which died later from the infection. 

 Janda and Jirovec (1937) injected bacteria-free culture of this 

 ciliate into annelids, molluscs, crustaceans, insects, fishes, and 

 amphibians, and found that only insects — all of 14 species (both 

 larvae and adults) — became infected by this ciliate. In a few days 

 after injection the haemocoele became filled with the ciliates. Of 

 various organs, the ciliates were most abundantly found in the 

 adipose tissue. The organisms were much larger than those present 

 in the original culture. The insects, into which the ciliates were in- 

 jected, died from the infection in a few days. The course of develop- 

 ment of the ciliate within an experimental insect depended not only 

 on the amount of the culture injected, but also on the temperature. 

 At 1-4°C. the development was much slower than at 26°C; but if 

 an infected insect was kept at 32-36°C. for 0.5-3 hours, the ciliates 

 were apparently killed and the insect continued to live. When 

 Glaucoma taken from Dixippus morosus were placed in ordinary 

 water, they continued to live and underwent multiplication. The 

 ciliate showed a remarkable power of withstanding the artificial 

 digestion; namely, at 18°C. they lived 4 days in artificial gastric 

 juice with pH 4.2; 2-3 days in a juice with pH 3.6; and a few hours 

 in a juice with pH 1.0. Cleveland (1928) observed Tritrichomonas 

 fecalis in faeces of a single human subject for three years which grew 

 well in faeces diluted with tap water, in hay infusions with or with- 

 out free-living protozoans or in tap water with tissues at —3° to 

 37°C, and which, when fed per os, was able to live indefinitely in 

 the gut of frogs and tadpoles. Reynolds (1936) found that Colpoda 

 steini, a free-living ciliate of fresh water, occurs naturally in the 

 intestine and other viscera of the land slug, Agriolimax agrestis, the 

 slug forms being much larger than the free-living individuals. 



It may be further speculated that Vahlkampfia, Hydramoeba, 

 Schizamoeba, and Endamoeba, are the different stages of the course 

 the intestinal amoebae might have taken during their evolution. 

 Obviously endocommensalism in the alimentary canal was the 

 initial phase of endoparasitjsm. When these endocommensals began 



