STUDIES ON AVIAN H.EMOPEOTOZOA. 723 



Again, with respect to the so-called " indiiferent " indi- 

 viduals, which are very scanty in nuinber, compared with the 

 female or male forms, figs. 15, 17, and 64, show the character- 

 istically clear cytoplasm, not at all granulai*, and staining very 

 faintly, of these individuals — readily distinguishable from 

 the granular, deeply staining cytoplasm of female forms. ^ 

 Further, in most of the parasites of this kind which I have 

 found, the kinetonuclear element is relatively large, and 

 may approximate in size to the other nucleus (cf. fig. 64). 

 What exactly is to be understood by the term " indifferent " 

 as applied to these forms, and what their significance is, it is 

 diflBcult to know. If they are neither male nor female they 

 are not gametocytes ; that much is obvious. At the time 

 when I wrote my earlier note on this Halteridium, I was 

 strongly inclined to think that these neutral individuals 

 passed, in certain conditions or circumstances, directly into 

 small trypanosomes. Unfortunately I have not been able to 

 obtain any more evidence in support of this view, either from 

 a renewed study of my own preparations of the chaffinch 

 parasite, nor — which is even more important — from the study 

 undertaken of Halteridium noctuse, so far as this has yet 

 progressed. Hence the meaning of these "indifferent" 

 individuals, which certainly appear to be quite distinct from 

 the forms of male or female character, has still to be ascer- 

 tained. I have never found indications of division in them, 

 any more than in the other types. 



In fig. 16 is di-awn one of the two or three instances I have 

 observed of the remarkable form of individual occurring free 

 in the blood-plasma, which shows a conspicuous line running 

 down the greater part of the body, near one side. This line 

 stains distinctly red, like a flagellum ; it appears to start in 

 close proximity to the nuclear masses, and ends in a definite 

 granule. The pigment-grains in this parasite are all aggre- 

 gated together near one end of the body — that farther away 

 from the nuclei. I regarded the halteridia in this phase 



' Of course there is no possil^ility of confusing these forms with male 

 gametocytes, which have a lai-ge, diffuse, pale-staining nucleus. 



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