26 
2. Further remarks on the flagellate parasites of Culex. Is there a generic 
type, Crithidia? 
By H. M. Woodcock, D. Sc., Lister Institute of Preventive Medicine, London. 
(With 1 figure.) 
eingeg. 3. Januar 1914. 
In a preceding Note in this Journal (Zool. Anz. Vol. 53, No. 8, 
p. 370). I have described the various forms of a parasite found in 
hibernating Culex pipiens, which I have regarded as “Crithidia” 
fasciculata Léger (1). These forms agree on the whole closely with 
those described by Novy, McNeal and Torrey (2) from the same 
Insect, which they also refer to Léger’s parasite. I pointed out, 
however, that I was quite unable to see anything that could be safely 
interpreted as an undulating membrane, either from the movements of 
the parasites, both short and elongated forms, or from their appearance 
in fixed and stained preparations. In regard to this point, the account 
of the American authors is somewhat confusing. In one place they say 
that in this form the existence of such an organella could not be satis- 
factorily established. A little further on, however, they state that, in 
certain of the longer individuals, a distinct wave-motion at the anterior 
end could be seen in life, giving evidence of the presence of a membrane; 
and they conclude finally that this parasite (“C.” fasciculata) has an im- 
perfect (i. e. rudimentary) membrane. Having regard to these last defi- 
nite statements of Novy, McNeal and Torrey, I considered that 
probably the reason why none of my forms shewed any membrane was 
because they occurred in fasting females and were only rejuvenated, as 
it were, into activity by the addition of the fluid in which they were 
examined; whereas those investigated by the American authors were 
always examined at a period when some hours had elapsed after a meal 
of blood, when the parasites were swarming in the stomach. For there 
can be no doubt, I think, that both they and I have been dealing with 
the same form. 
On the other hand, Léger, in his original account of ©. fasci- 
culata, figured a phase with a quite unmistakeable membrane, extending 
along part of the body and for some distance along the flagellum, as 
belonging to this parasite. The American workers suggested, as an 
explanation to account for this discrepancy, that Léger was really 
dealing with a mixed infection and had included phases belonging to 
two distinct parasites in his description; this view was also taken by 
Patton (3). As supporting their suggestion, Novy, McNeal and 
Torrey shewed clearly (so far as can be judged) that a mixed infection | 
does occur in the “wild” Culex, and separated a parasite which they 
