648 J. S. DUNKERLY. 



use of tlie name Critliidia,, tin's is certainly a misuse of Leger's 

 term, wliicli .lie applied (8) to a short rounded form, " en 

 form de grain d'oi'ge legerement aplati et tronque al'extremite 

 anterieure . . . /' and usually without an undulating mem- 

 brane. However, it seems from the evidence of the forms 

 found ill Horaalomyia that the same organism may be without 

 an undulatiDg membrane at onestiige of its life-history, while 

 possessing one at another stage. I shall return later in 

 this p;iper to this question of nomenclature. 



(3) In the rectum, near the rectal glands, were found 

 masses of small oval bodies (PI. 31, fig. 15) attached to the 

 rectal epithelium. On examining these in water I was able 

 to observe the mass apparently swell, as though the walls of 

 the oval bodies were gelatinous, :ind after a short time some 

 of the bodies were seen to become actively motile, with a 

 small .'Ulterior flagellum (PI. 31, figs. 16 and 17). The flies 

 containing these C3^sts had no other flagellate stages in them, 

 but came from the same locality as those that had. Similar 

 cysts have been described by Miiichin (15) for T. grayi, by 

 Prowazek (20), Kosenbusch (21), and Mackinnou (14) for 

 Herpetomouas, the latter having observed them giving rise 

 to flagellates. The cysts stained with Giemsa (PI. 31, fig. 15) 

 show a faint trophonucleus and a distinct kinetonucleus, with 

 a large number of scattered granules stained a deep purple 

 colour, and have a definite wall surrounded by a remark- 

 able substance which stains deeply, and may be gelatinous in 

 nature (vide supra). But irou-hiumatoxylin shows little of 

 these peculiar effects (PI. 31, fig. 17a). The commencement 

 ot" development of the flagellum is indicated by a clear area in 

 (liemsa preparations (PI. 31, fig. 15b), the borders of which 

 appear to stain with iron-haematoxylin, showing a triangular 

 area witli the kinetonucleus as base (PI. 31, fig. 17a and d), 

 and the same appearance has been seen in non-flagellate 

 forms of T. lewisi by Prof. Minchin, wdio kindly showed 

 me his original drawings. 



In the Iife-C3'cle of Leptomonas, as far as I have investi- 

 gated it, we find the following forms: (1) A typical Lepto- 



