256 E, A. MINCHIN. 
less strongly marked, of the common intermediate type ; 
secondly, that the difference between the extreme forms is 
not one of dimensions alone, but of points of structure and 
morphology which Salvin-Moore and Breinl have overlooked. 
I am content to let my figures speak for themselves. 
Since my work relates almost exclusively to the develop- 
ment of Trypanosoma gambiense in the tsetse-fly, I have 
no comment to offer on the cycle in the blood, with formation 
of latent forms, described by Salvin-Moore and Breinl; a 
discovery of the highest importance, if true, but which does 
not, in my opinion, disprove the existence of a developmental 
cycle in an invertebrate host. It is possible, however, that 
the pathogenic trypanosomes as a group may owe their 
peculiar properties to having become adapted exclusively to 
vertebrate hosts ; but in that case the problem of transmis- 
sion and infection becomes difficult to understand.  Salvin- 
Moore and Breinl state (p. 446) that the blood during 
negative phases, “even if it be properly filtered, is still 
capable of infecting.” his is a very important statement, 
and I look forward with much interest to the publication by 
the authors of the evidence on which it is based. At present 
they have given us none. 
Lister Institute, January 15th, 1908. 
DESCRIPTION OF PLATES 8—13. 
Illustrating Prof. HK. A. Minchin’s paper on, “ Investigations 
on the Development of Trypanosomes in T’setse-Fhes 
and other Diptera.” 
All the figures are drawn with the camera lucida to a magnification of 2000 
diameters, except, Figs. 102-110, Figs. 122-125, and Figs. 127-130 on Pl. 10, 
which are freehand sketches. 
PLATE 8. 
Trypanosoma gambiense. 
Vtes. 1-5.—From the blood of Monkey 478, on Octoher Ist, 1905 (pp. 176 
and 230). 
