TRYPANOSOMES IN BIRDS 563 



type of crithidia, these elongate, become trypanosome-like and later 

 are endowed with an undulating membrane. After the typical 

 trypanosome shape has been developed a trophonucleus is seen as a 

 fair-sized vesicle, containing coarse chromatin granules. The kineto- 

 nucleus (micronucleus) is usually elongated, forming a long ellipsoid, 

 and stains an almost black-garnet color. The two nuclei are always 

 close together. The undulating membrane is well developed. The 

 parasites appear under two forms, a band-shape and a club-shape. 

 The band-shaped forms are more typical trypanosomes, and are more 

 numerous than the others. In all the cultures the trypanosomes tend 

 to occur in great clusters. These must not be confounded with 

 agglutination rosettes, which present a wholly different appearance. 

 In the clusters nothing in the way of a definite orientation can be 

 made out, while in the agglutinations seen the arrangement was 

 radial. 



Observations similar to those made by Crawley had previously 

 been made on Japanese cattle by Miyajima, who, however, believed 

 that the trypanosome which he obtained in cultures represented a 

 stage in the life cycle of a non-pathogenic piroplasma. The obser- 

 vations of Miyajima and Crawley as to the development of trypano- 

 somes from healthy cattle when their blood is mixed with nutrient 

 bouillon need further confirmation before they can be fully accepted. 

 It is not to be forgotten that the blood platelets when blood is mixed 

 with certain culture media often assume shapes which may be 

 easily mistaken for trypanosomes. 1 



Trypanosomes in Birds. Trypanosomes in birds have been studied 

 extensively by Novy and MacNeal. They undertook these studies 

 particularly on account of Schaudinn's claim that trypanosomes in 

 birds were a stage in the life history of the avian intracorpuscular 

 parasite halteridium (Hsemoproteus noctuse). Schaudinn, on allowing 

 the common mosquito (Culex pipiens) to feed upon the blood of owls 

 infected with halteridium, found in the intestines of about 10 per cent, 

 of these insects large numbers of trypanosomes which he considered a 

 cycle in the life stage of the Hsemocytozoon halteridium. Novy and 

 MacNeal cultivated such trypanosomes from mosquitos in test-tubes 

 on the blood-agar medium. The trypanosomes multiplied readily, but 

 the hematozoa died out. When birds were infected with such pure 

 cultures of trypanosomes no intracellular parasites developed. The 

 cultivation of the bird trypanosomes, according to Novy and MacNeal, 

 is as easy as that of the rat trypanosome. They concluded from their 

 studies that trypanosome infection is very common and widespread 

 in birds, that different avian species harbor different trypanosomes, 

 and that one bird may be infected by several species of trypanosomes. 

 The latter are not pathogenic for birds, but evidently harmless para- 

 sites. 



1 Swingle has recently called attention to this fact in a paper published in the Journal of 

 Infectious Diseases. 



