130 
MURIEL ROBERTSON. 
I cannot agree with Capt. Patton and Mr. C. Strickland, 
who, on the basis of tuy previous description, consider this 
parasite to be an independent Crithidia having no connection 
with T. raiae. In a recent paper ^ I observe that they place 
it in this group with the name of C. robertsoni. I would 
like to point out that, quite apart from the question as to 
whether this parasite belongs to the cycle of T. raim or not, 
it certainly is a Trypanosome. The Crithidial, like the Her- 
petomouad stage which precedes it, is transitory; the animal 
ultimately adopting the Trypanosome state. I admit at once 
that the distinction between a Crithidia and a Trypanosome 
is not a very important one, but, such as it is, I do not see 
that there is any scientific point in neglecting it. 
I now wish to give a brief account of the parasite as seen 
in stained films, fixed, for the most part, in Schaudinu’s 
(alcohol-acetic corrosive sublimate) fluid. The stains used 
were Delafield’s hmmatoxylin, Heidenhain’s iron liEematoxylin, 
T wort’s licht-griin, and neutral red combination and fuchsin. 
Delafield gives an excellent result, staining the nuclear 
structures with clearness and precision; the flagellar appa- 
ratus stains, but does so a little faintly. 
Iron haematoxylin gives a very clear picture, staining the 
nuclear parts coal black, and bringing into good relief flagellar 
and cytoplasmic detail. Great cai'e, however, must be taken 
in the interpretation of this stain, as it leads one into much 
the same errors as Giemsa’s method, in so far as it stains 
chromatic and acromatic structures alike. Tberefore, while 
lleidenhain’s method gives a really splendid picture, it is 
necessary to check the results by Delafield’s limmatoxylin, 
which is a much safer stain. 
Twort’s combination of neutral red and licht-griin was also 
used. This is a clear, transparent stain, giving a red reaction 
' “A Critical Review of the Relation of Blood-sucking Invertebrates 
to the Life Cycles of the Trypanosomes of Vertebiates, etc.," by 
Captain Patton and C. Strickland. ‘ Parasitology,’ vol. i, No. 4, Dec., 
iyu8. 
