7] 2 H. M. WOODCOCK, 



Again, Novy, McNeal, and Torrey, in their paper on tlie 

 flagellates of mosquitoes (15), distinguish two parasites, 

 namely, Crithidia fasciculata and Trypanosoma 

 (Herpetomonas) culicis. These authors also followed 

 Leger's unfortunate definition of a Crithidia, restricting the 

 name to small oval or pyriforni parasites with a truncated 

 flagellar end and a short flagellum. The whole objection to 

 this definition lies in the fact that such forms are merely 

 resting or attached phases (in natural conditions) of either 

 crithidial (trypanomonad) or herpetomouad forms. However, 

 in the case of their Crithidia, the figures given show that, 

 in a more elongated condition, it conforms on the whole to 

 the trypanomonad type. Similarly, their other parasite, 

 Trypanosoma (Herpetomonas) culicis, also has a well- 

 marked trypanomonad ]diase, as, indeed, is implied by the 

 generic position which the authors assign to it; apparently 

 it is phxced in the sub-genus Herpetomonas because of its 

 monadiue form. I may observe here that these papers by 

 the American authors have been most diflScult for me to 

 comprehend, because the indications afforded or suggested by 

 their plates often appear to be opposed to the account given 

 in the text. I have only really grasped the significance of 

 their first paper on avian parasites and their cultural forms 

 since working on my own birds and cultures; and I am sure, 

 from the interesting plates of mosquito-parasites in the 

 authoi's' second paper, that a further study of the phases and 

 forms which they figure is essential to a correct understanding 

 of their significance. Hence I do not propose to criticise 

 them further at present. 



This much, however, must be said iu regard to all these 

 cases of the occurrence of trj^panomonad forms in mosquitoes. 

 It is at least quite as likely that the flagellates observed 

 were phases of vertebrate trypanosomes — say of avian forms 

 — as that the}^ were purely insectan parasites. I have referred 



say here that in the development of T. noctuse in Culex pipiens 

 I have not come across the slightest indication of a herj)eto monad 

 phase. 



