580 FAMILY: TRYPAXOSOMIDiE 



identification of species exceedingly difficult, especially as the majority 

 of those which have been named have only been seen in one particular 

 phase in a single blood-film. Furthermore, very little is known as to the 

 number of hosts any trypanosome may infect. As noted above, Thiroux 

 (1905) found that T. jJaddce was inoculable to a number of different birds. 

 Similarly, Noller (1920c) found that T. loxice of Loxia curvirostm was 

 inoculable to canaries and finches. 



Though trypanosomes have been described from many different birds, 

 they can all be referred to one or other of the types described by Minchin 

 and Woodcock as occurring in the cycle of development of the trypano- 

 some of the little owl, Athene noctva, and which are illustrated in Fig. 235. 

 As regards the details of their morphology, bird trypanosomes conform to 

 other members of the genus. Nieschulz (1922a) has described a rod- 

 shaped structure which occurs in the cytoplasm of cultural forms and a 

 granule which is present on the nuclear membrane. These have already 

 been referred to above (Fig. 154). 



Transmission. — As regards the natural transmission of bird trypano- 

 somes very little is known. Schaudinn (1904), and later Woodcock 

 (1914), stated that C. pipiens was the intermediate host of T. noctucB. 

 Danilewsky observed that young birds in the nest only a few days old 

 were already infected with trypanosomes. Duke and Robertson (1912) 

 noted that T. gallinarum (Fig. 235, ii), first described by Bruce et al. 

 (19in) in Uganda fowls, underwent a development in Glossina palpalis, 

 resulting in the production of crithidia forms in the stomach. It was 

 concluded, however, that the tsetse fly was not the true host. What is 

 possibly the same trypanosome was seen by Mathis and Leger (1911a) 

 in fowls in Tonkin. It is probable that the transmitting hosts of bird 

 trypanosomes will have to be sought amongst the blood-sucking arthropods, 

 which especially infest the nests. There is evidence, however, that bird 

 trypanosomes will develop in mosquitoes. Woodcock (1914) described 

 the changes undergone by T. noctuce in C. pipiens. The trypanosomes 

 taken up by the mosquitoes underwent multiplication and became 

 crithidia forms, while finally long slender trypanosomes and very much 

 rmaller stumpy trypanosomes were produced. The latter forms bear a 

 resemblance to the metacyclic trypanosomes which are developed in the 

 hind-gut of the flea in the case of T. lewisi. Noller (1920c) also noted 

 that T. loxice underwent a development in C. pipiens, as also in A'edes 

 argenteus. This culminated in an accumulation of flagellates in the hind- 

 gut of the mosquitoes. He noted that when T. loxice and T. syrnii were 

 cultivated on blood-agar plates at 18° to 20° C, there was rapid multiplica- 

 tion of crithidia forms, and that a transformation into trypanosomes 

 took place when the plates were incubated at 37° C. In cultures of T.frin- 



