TRYPANOSOMES OF NEWTS AND FISH 599 



inactivated at 56° C. for thirty minutes and distilled water. In this 

 mixture T. rotatorium will not develop. 



According to Brumpt (1914a), T. lejdodactyli of the Brazilian frog, 

 Leptodactylus ocellatus, undergoes a complete development, terminating in 

 the appearance of metacyclic trypanosomes in the proboscis sheath, in the 

 leech, Placobdella hraziliensis. 



Lloyd, Johnson, Young, and Morrison (1924) have shown that labora- 

 tory bred Glossina tachinoides in Nigeria develop a crithidial infection of 

 the intestine after feeding on toads, Bufo regularis, which harbour trypano- 

 somes resembling T. varani. 



{b) Trypanosomes of Urodeles. 

 A trypanosome in an American newt {Diemyctyhis viridescens) was 

 described by Tobey (1906) under the name of T. diemyctyli. The body of 

 the trypanosome measures 45 to 50 microns, and there is a fiagellum 

 24 microns in length. The breadth varies from 2 to 5 microns. The undu- 

 lating membrane is well developed. Hegner (1921) has called attention 

 to the frequency with which these newts are infected. Ogawa (1913) 

 described a trypanosome named by him T. tritonis from the Japanese 

 newt, Triton jpyrrhog aster. It measures 57 to 80 microns in length by 

 2-4 to 6-4 microns in breadth. The fiagellum is about 15 microns long. 

 It was readily cultivated in bouillon to which a tenth part of defibrinated 

 rabbit's blood had been added. 



3. Trypanosomes of Fish. 



The trypanosomes of fish have attracted attention since Valentin's 

 discovery of what was either one of these flagellates or a trypanoplasm in 

 the blood of a trout (Salmofario) in 1841. A large number have since been 

 seen in both fresh and salt-water fish in various parts of the world, and 

 many of them have been given specific names. In some cases there is 

 evidence that one and the same trypanosome may have several hosts. 



Morphology. — The trypanosomes of fish usually have long and narrow 

 bodies (Fig. 243). When observed alive, they wriggle about in a peculiar 

 snake or worm-like manner, and frequently roll themselves into knots, 

 only to extend themselves again. The trypanosome of a ray (T. giganteum) 

 may be as much as 130 microns in length, while that of the pike (T. retnaki) 

 may have a body only 15 microns long. The majority of forms are about 

 50 microns in length, with a breadth of 2 to 5 microns. There is a fiagellum 

 of varying length and a well-developed undulating membrane. The kine- 

 toplast is generally large, and the nucleus, which is often easily visible 

 in the living trypanosome, is centrally placed. Sometimes, as in the 

 case of T. remaJci, two types of trypanosome are present in the blood 



