246 Crithidia puliGis n. sp. 
occurring therein is a developmental form of a trypanosome, or a true 
parasite of the insect. 
My own work on (7. pulicis confirms the statement that natural 
flagellates can occur in sanguivorous insects, and in this case there is 
certainly no evidence to show that the results obtained on C. pulicis 
from “ wild ” P. irritans could be regarded as “ almost guesswork.” 
As with the Tahanidae, a natural flagellate of the host is present, and 
there is not one tittle of evidence to show that G. pulicis is other than a 
natural flagellate of P. irritans. 
Arm-chair criticism is always easy and after five minutes of wdld 
hypotheses, the march of progress may be endangered for as many years. 
This has recently been attempted by certain dogmatic individuals who 
have published compilations regarding trypanosomes, Gritliidia and 
Herpetomonas without really practical knowledge or first-hand investi¬ 
gation of some of the subjects discussed. But having formed an 
hypothesis, they then support it blindly. Further, though the hypo¬ 
thesis has been shown by recent research to be untenable, yet they 
continue to preach the same, and, as with the importunate friend, gain 
a hearing and obtain followers by their very insistence. The following 
so obtained is not of the highest order, needless to say, as witness a 
recent deluded beginner, who in his first essay in the investigation of 
the flagellates of flies, states of a man who has never published an 
original paper on Herpetomonas, and has merely confused the whole 
subject in a wordy text-book, that the history of Herpetomonas is 
related in greater detail by him ! British Protozoology is in a bad way 
when original work is neglected, or confused with that of the mere 
compiler. 
While writing this paper, my attention has been drawn to an 
account published by Mr J. S. Dunkerly on a parasite or parasites 
which he calls Leptomonas muscae domesticae. Most of his paper, 
however, is devoted to an attempt to discuss the genera Leptomonas, 
Herpetomonas, Crithidia and Trypanosoma. I would nob trouble to 
notice the paper, except that in it the author attempts to establish that 
Ci'ithidia is not a valid genus and he states (p. 649) that “ It is with 
a view to the clearing up of at least one part of the vexed question 
[nomenclature] that I wish to re-state the following facts in their 
history.” Indeed ! This is rather an ambitious task to essay in one’s 
first paper on such a complicated subject as the Flagellates of Insects. 
But Mr Dunkerly is nothing if not courageous. However, I beg to 
inform him that a much broader and more accurate view will have to 
