THE HiEMOFLAGELLATES. 179 



"araceboid" and "plasraodial" forms.' These evideuces of 

 commencing degeneration or slow death of the parasites are 

 often numerous in the spleen, lymphatic glands, and the bone 

 marrow (especially of spleenless hosts), and, of course, are 

 also met with in the general circulation. Bradford and 

 Plimmer say that they have observed phagocytosis only of 

 such forms, and not of tj^pical adults. This is in favour of 

 the view that these forms are abnormal, already weakened by 

 some agency of the host, and, therefore, less capable of 

 resisting ingestion by the leucocytes. It is these altered 

 forms which are especially liable to block the cerebral capil- 

 laries. Their morphology will, however, be more conveniently 

 discussed after considering that of typical Trypanosomas. 



Section V. General account op Trypanomorpha (Try- 

 panosoma) NOCTU^ (Celli and San Felice). 



(A scheme indicating the principal phases of the life- 

 history, and serving as a general summary, is given on 

 p. 180.) 



In the life of Trypanomorpha noctua?," parasite of 

 Athene noctna and Culex pipiens, the Trypanosome 

 phase is so frequently lost sight of — the parasite passing into 

 the Hasmosporidian phase, when it takes the form of a Halt e- 

 ridium — that certain stages in development are most easily 



' IMcNeal (74) would assign the destruction of tlie Trjpanosonies to the 

 cytolytic agents in the peritoneal fluid, which bring about their immobi- 

 lization and gradual solution, rather than to phagocytosis. 



- This parasite has been selected as an example of the complete life-cycle 

 oE a Trypanosome, not as intending to imply that it is in every way typical 

 o£ the majority, but because, when the jilan of this article was arranged, 

 choice was limited to one of the two forms described by Schaudinn. Try- 

 panomorpha (and still more, Trypanosoma ziemanni) has advanced 

 further in the direction of the Hremosporidia than, for instance, Jlammalian 

 Trypanosomes probably have. Nevertheless, there can be little doubt that, 

 as regards the chief features of its biology, morphology, and life-history, 

 this parasite may be considered as a representative Hsemoflagellate (see 

 below, under "Comparative account of the life-cycle"). 



