6 PROF. E. A. MINCHIN ON PROTOZOAN (Jan. 12, 
the Aagella very sharply, but were too opaque for internal struc- 
ture; I therefore had the parasites drawn in outline with the 
camera lucida, then unmounted the coverslip, extracted more of 
the stain, and, after mounting it again, added the details of minute 
structure to the drawings already made. ; 
With use of iron-hematoxylin in never-dried preparations 
suitably fixed, absolutely uniform results are obtained with regard 
to the nuclear structure. When two such staining methods as 
the Romanowsky stain and the Heidenhain stain give conflicting 
results in matters of nuclear detail, no one with any knowledge 
of cytological methods would hesitate, I think, to regard as more 
reliable the evidence yielded by the Heidenhain stain. 
The figures illustrating this memoir were drawn with the camera 
lucida to a magnification of 2000 linear, with the exception of the 
sketches drawn from living trypanosomes (figs. 77, 94, 95). The 
majority of the drawings were executed by my assistant Miss 
Rhodes, to whom I desire to express my thanks for her skilled 
help in this work, 
General Remarks on the Trypanosomes and Trypanoplasms 
of Fishes. 
It would, perhaps, be more logical if the general account of 
these parasites came after the detailed descriptions of the species, 
since the conclusions at which I have arrived are founded on the 
data which are set forth in the special descriptions. But to many 
the general summary of results that is given here will be of greater 
interest than the, perhaps, rather wearisome special details, which 
therefore I relegate to second place, for purposes of reference for 
those specially interested. 
From a study of the trypanosomes of fishes in the fresh, living 
condition in the blood, I have come to the conclusion that there 
are two types of movement: a conclusion which may perhaps be 
true of trypanosomes universally. Sometimes they may be seen 
to move in a definite direction ; at other times they are seen to be 
twisting about in one spot without moving from it. Iterm these 
two types of movement travelling and wriggling respectively. 
They travel usually with the flagellum forwards ; in the trypano- 
some of the eel I have observed progression of this type only. 
Some trypanosomes, however, can be seen to travel occasionally 
with the flagellum directed backwards ; progression in this manner 
appears to me to occur chiefly when the trypanosome is forcing 
its way through corpuscles, and never when its path is unobstructed. 
Im either case, however, progression appears to be effected chiefly 
by flexions of the whole body and by rippling movements of the 
undulating membrane, and scarcely at all by means of the free 
flagellum. 
In wriggling movements the trypanosome simply twists over 
and over in S-like curves in one spot, and often appears as if tied 
in a knot; this is what I understand Laveran and Mesnil to mean 
