TRYPANOSOMA 59 



about the division of the flagellum, and the division of the 

 flagellum is followed by the division of the whole body. The 

 duplication of the flagellum begins at the point of origin and 

 terminates at the free end ; the duplication of the body proceeds 

 dorso-ventrally, but the division forms do not separate along the 

 ventral border until the newly-formed flagellum has entirely parted 

 from the old one, thus the separation of the division forms pro- 

 ceeds from the tail end forwards. One frequently sees parasites 

 still adhering by their anterior extremities. The division forms 

 are of about equal size and slightly smaller than the parent form. 

 Amongst these asexual forms we occasionally find some larger 

 forms which are analogous to the macrogametes of the malaria 

 parasites ; as a rule, these forms do not divide until after copu- 

 lation, which probably in most species takes place in the body of 

 an alternative host. They are characterised by a larger size, 

 which may be more than double that of the asexual forms, by 

 a stumpy shape, by a short flagellum and by the presence of 

 numerous chromatophores. Sometimes vacuoles are found in the 

 plasma of these forms. They end by becoming almost round and 

 losing entirely their flagellum. By the side of these female 

 forms we meet some very slender hyaline forms with very long 

 flagellum, with comparatively large nucleus and large blepharo- 

 plast. They are the male forms or microgametes. The number 

 of the sexual forms varies greatly in different slides. At times 

 they are quite numerous. 



The life-history of the trypanosomes is very superficially 

 known. Quite recently Dr. Fritz Schaudinn has studied the 

 entire life cycle of Trypanosoma noctuce, a trypanosome of the 

 little owl (Athence noctuce), the gametes of which were described 

 in 1891 by Celli and Sanfelice under the name of Hcemoproteus 

 (= Halteridium) noctuce. I will give a brief sketch of the life- 

 history of Trypanosoma noctuce as a guide to the study of the 

 bionomics^ of other species. Trypanosoma (= Halteridium) noctuce, 

 like Hcemamceba relicta (Proteosoma), insures the continuancy of its 

 existence by an alternation of generative processes and by a 

 change of hosts. Its intermediary host is the little owl (Athence 

 noctuce), its definitive host is Culex pipiens. 



When first introduced into the blood of the bird, the para- 

 sites have the form of trypanosomes, but they are as a rule very 

 small. They attach themselves to the erythrocytes, discard their 

 flagella and assume the well-known halteridium form. After about 

 twenty-four hours, granules of pigment begin to appear in their 



