254 Crithidia 2 >idicis n. sp. 
Fig. 8. Kosette, showing unequal rate of development of the pre-flagellates. 
Figs. 9-17. Flagellates of C. pulicis. 
Fig. 9. Small flagellate, showing nucleus, well-marked blepharoplast and body myoneme. 
Fig. 10. Larger parasite, showing oblique blepharoplast and very chromatoid nucleus. 
Fig. 11. Flagellate with broad posterior end. 
Fig. 12. Broad form. 
Fig. 13. Parasite showing twist of the posterior end of body. Such an appearance is 
often seen in life. 
Fig. 14. Very narrow form, a division product of such forms as shown in figs. 15-17. 
Figs. 15-17. Large flagellates, showing the very characteristic prominent membrane with 
myonemes. These forms are common. 
Figs. 18-22. Stages in the division of C. pulicis. 
Fig. 18. Broad form showing beginning of division of the blepharoplast. 
Fig. 19. Shows parasite with dumb-bell shaped blepharoplast and flagellum beginning 
to split. 
Fig. 20. Parasite showing complete division of blepharoplast and membrane, nucleus 
constricted. 
Fig. 21. Separation of two daughter forms in symmetrical fission. 
Fig. 22. Asymmetric division of C. pulicis. Separation of daughter forms almost 
complete. 
Figs. 23-36. Post-flagellate stages of C. pulicis. 
Figs. 23-25. Shortening forms showing concentration of protoplasm round the nucleus 
and blepharoplast and retraction of the flagellum. 
Fig. 26. Cluster of four parasites, one of w'hich has become the typical post-flagellate, the 
other three being not quite so advanced. 
Figs. 27, 28. Almost complete assumption of the post-flagellate form. Fig. 28 x 1950. 
Figs. 29-33. Post-flagellates showing variation in size. 
Figs. 34-36. Post-flagellates in which the contents are somewhat shrunken away from 
the thin varnish-hke wall. 
