142 
Haemoflagellates, etc. 
author considers the flagellates found in the species of Conorrliinus are 
developmental forms of T. minasense or stages of some other vertebrate 
trypanosome. We know of a species of Conorrliinus ( C. rubrofasciatus ) 
in Madras in which Donovan (1909) has found a true critliidia. It is 
therefore most probable that T. cruzi is also a natural crithidia of the 
bug and it would be important to know how it is transmitted from one 
bug to another. There is no proof in Chagas’ preliminary note to show 
that T. cruzi is a vertebrate trypanosome. 
The last paper we wish to refer to is by Swingle (1909); this author 
describes in some detail the life-cycle of Crithidia melopliagia Flu.; he 
has come to the conclusion that this flagellate has nothing to do with 
the sheep, but is a true parasite of Melophagus ovinus. We entirely 
agree with this view and consider it is the only possible explanation of 
its occurrence in the alimentary tract of the sheep “ ked.” Swingle 
brings forward some sound evidence to show that this crithidia is most 
probably transmitted through the eggs of the insect, as he has been able 
to find its post-flagellate stages in sections of the ovaries. There appears 
however to be an attempt at true cyst formation such as we have 
described for Crithidia gerridis and Crithidia tabani. 
With regard to the biological position of this parasite Swingle con¬ 
siders it is intermediate between crithidia and herpetomonas. We 
however have no doubt that it is a true crithidia, and exactly answers to 
our (1909) definition of this genus. Swingle rightly points out that if 
Novy, MacNeal, and Torrey’s (1907) nomenclature is to be followed 
Crithidia melopliagia would be neither a crithidia nor a herpetomonas, for 
according to the American observers herpetomonas has an undulating 
membrane. This we cannot agree with ; all the herpetomonads we have 
studied have no undulating membrane, while all the crithidia have. As we 
have pointed out elsewhere, the American observers’ characterisation of 
the crithidia is based on Leger’s unfortunate description of C '. fascicidata. 
Donovan (1909), who has studied these parasites under the most favour¬ 
able conditions, viz. in the alimentary tracts of their hosts, is entirely of 
our opinion, and we cannot do better than quote his remarks. He says: 
“ There appears to be still a considerable amount of confusion, one may 
say ignorance, of the three parasitic genera, Herpetomonas, Crithidia and 
Trypanosoma ; all forms not in possession of an undulatory membrane 
and a posteriorly placed blepharoplast are loosely called ‘ herpetomonas 
forms ’ or ‘ wild trypanosomes ’ (sic). As I have had under observation 
during the last 18 months a number of these three genera I may be 
pardoned for my presumption in setting this question on a sounder basis. 
