TRYPANOSOMES OF LAND REPTILES 581 



gillinanim, Woodcock (1914) likewise noted that a trypanosome phase 

 followed the appearance and multiplication of crithidia forms. It is 

 evident that the cycle of development of bird trypanosomes in the inverte- 

 brate will follow the usual lines, in which crithidia forms first appear, to 

 be followed by metacyclic trypanosomes. No actual transmission by 

 means of mosquitoes or any other invertebrates has as yet been effected. 

 An interesting observation made by Mathis (1914) may be urged in support 

 of the view that the transmitting hosts of bird trypanosomes are mos- 

 quitoes. In a species of Ciilex in Tonkin he noted an infection of the 

 salivary glands with flagellates of the crithidia type, and conjectured that 

 these might have been derived from some bird trypanosome (p. 370). 



Culture. — That trypanosomes of birds are relatively easy to cultivate 

 in blood-agar media was first demonstrated by Novy and McNeal (1905). 

 Danilewsky (1888), however, had previously observed multiplication of 

 trypanosomes in hanging-drop preparations of bird's blood. Novy and 

 McNeal, and Nieschulz (19226) noted that infections could be demonstrated 

 in birds by the cultural method w^hen blood-examinations were negative. 

 In these cultures the trypanosomes multiply rapidly, becoming trans- 

 formed into crithidia and rounded or ovoid forms. In older cultures 

 trypanosomes again appear. The cultures may be maintained indefinitely 

 by subculture. Novy and McNeal, and Thiroux (1905) found that birds 

 were with difficulty infected from the cultural forms. 



Noller (1920c) and Nieschulz (19226) have cultivated trypanosomes 

 from a number of birds on blood-agar plates. The plates kept at room 

 temperature show mostly crithidia forms. If they are kept at 37° C, the 

 crithidia forms assume the trypanosome structure, but again revert to 

 the crithidia form when the temperature is reduced. 



IV. TRYPANOSOMES OF LAND REPTILES INCLUDING CROCODILES. 



The first definite record of a trypanosome in a reptile was that of 

 Laveran and Mesnil (1902), who described T. damonice of the tortoise, 

 Damonia reevesii, though as early as 1883 Kunstler had noted a flagellate 

 in the blood of a mud tortoise, and considered it to be allied to the try- 

 panosomes. Since Laveran and Mesnil's discovery, various trypanosomes 

 have been described from crocodiles, tortoises, snakes, and lizards. 



In very few cases is the method of transmission actually known, but 

 such information as is available appears to indicate that the trypanosomes 

 of land reptiles, including crocodiles, are transmitted by blood-sucking 

 arthropoda, while those of aquatic reptiles are transmitted by leeches. 

 On this account the trypanosomes of reptiles are considered under two 

 headincrs. 



