432 
Degeneration of T. gamhiense 
this peculiar structure may extend to the anterior extremity of the cell, 
and there is no evidence to suggest that it ever becomes connected with 
the tropho-nucleus. On the contrary, the fact that it is only seen when 
numbers of the trypanosomes are degenerating, and the subsequent 
behaviour of the band, which gradually becomes less stainable (fig. 16) 
and breaks up into granules, clearly shew that it is merely one of the 
phenomena of degeneration. The “black line” was found to appear in 
some of the parasites 2—3 hours after an injection of arsenophenyl- 
glycin, even when no trace of it could be found in the trypanosomes 
immediately before treatment; and the fact that naturally it only occurs 
at the height of infection, when large numbers of degenerating forms are 
present, confirms the view that it is of no significance in the life history 
of T. gamhiense, but is merely a degenerating axial filament containing 
chromatic substance. The granules which arise from the breaking down 
of the axial filament very rapidly dissolve in the cytoplasm and dis¬ 
appear. 
In addition to the degeneration phenomena described above, after 
treatment one occasionally sees rounded up forms (fig. 25) which some¬ 
what resemble those described by Salvin-Moore and Breinl (1907) in 
T. gamhiense after treatment with atoxyl. There is no evidence, how¬ 
ever, to support the idea that they represent resistant forms, for we 
have never found any trace of them except during the first few hours 
after the injection of the drug. 
Summary of Results. 
After treatment with arsenophenylglycin the number of trypanosomes 
in an infected animal immediately begins to decrease, and the parasites 
disappear from the peripheral circulation 6—7 hours after the time of 
injection, the short stumpy forms being the last to degenerate. 
One of the first changes noticed in the trypanosomes after treatment 
is the rounding up of their posterior extremities caused by the retraction 
of the protoplasm behind the kineto-nucleus. Meanwhile the tropho- 
nucleus becomes filled with granules of volutinose, which are extruded 
into the cytoplasm and pass along the axial filament towards the 
anterior extremity of the body. In dividing forms the granules form 
two longitudinal rows, being distributed along the two axial filaments. 
Finally, the granules lose their regular arrangement and become 
scattered throughout the cytoplasm, being more abundant, however, at 
the anterior end. 
