40 Occurrence of Ency station in Trypanosoma grayi Novy, etc. 



disseminates the parasite, of a life-cycle which results in a contaminative 

 infection of the vertebrate host. 



A full account of the trypanosome-cysts described in this note, and of 

 other points relating to Trypanosoma grayi, will be published, with 

 illustrations, in the ' Quarterly Journal of Microscopical Science.' 



DESCRIPTION OF THE FIGURES. 



Figs. 1 and 2. — Free-swimming Herpetomo?ias-like forms of Trypanosoma grayi from the 



proctodeum of the tsetse-fly, before encystation has commenced ; iV., principal 



nucleus ; n., blepharoplast ; fl., flagellum. x 2000. 

 Fig. 3. — Commencement of encystation. The flagellum is becoming retracted, and the 



first appearance of the cyst-secretion is seen at O. x 2000. 

 Fig. 4. — Similar stage, slightly more advanced. The cyst- wall (C) is damaged at one 



point, x 2000. 

 Fig. 5. — Flagellum completely retracted, represented by a vacuole (fl. v.). X 2000. 

 Fig. 6. — The flagellar vacuole is absorbed and the flagellum is represented only by a 



delicate streak (fl. s.). Cyst much damaged, x 2000. 

 Fig. 7. — The cyst-secretion now extends all round the body, x 2000. 

 Fig. 8. — Rounded-off cyst, the final stage. Letters as before, x 2000. 



