196 ANNIE PORTER. 



Occasionally I have seen tlie flagellum and membrane of 

 specimens of C. melopliagia torn away from the body, and 

 for a few seconds after, the flagellum executed intermittent 

 flickers or lashing movements before it finally became still. 



Aggregation-rosettes (PL 12, figs. 41, 43; PI. 13, figs. 95j^ 

 96) are common in C. melophagia. Rosettes seem to move 

 fairly as a whole, and I have watched them rotate rather 

 quickly. Each individual of such a rosette is attached by 

 its flagellum to debris, usually epithelial in nature, and 

 moves up and down in a slightly inclined plane. 



In division the movements of the daughter organisms are 

 very noticeable. I will defer the description of their motion 

 until division is discussed. 



During encystment in the rectum of the host, which occurs 

 with some of the parasites, movement of the nucleus towards 

 the flagellar end of the organism occurred. I have also seen 

 the migration of the nucleus from the mid-region of the body 

 to near the flagellum during periods of violent movement of 

 the latter organella. I have never seen migration of the 

 blepharoplast in living organisms under similar conditions, 

 though it may occur at times, since blepharoplasts can occa- 

 sionally be found in the post-nuclear region (PI. 12, figs. 40, 

 42), as well as by the side of the nucleus (PI. 12, fig. 33) in 

 different stained specimens. By far the commonest position 

 for the blepharoplast is the pre-nuclear one. The other 

 movements occurring during encystment will be described in 

 the section of the paper dealing with that subject (see p. 200 

 and text-figures 1-10). 



Morphology. 



The life-cycle of Crithidia melophagia may be con- 

 veniently divided into three stages, which gradually merge 

 into one another. They are — the pre-flagellate, flagellate, and 

 post-flagellate stages. The morphology of these forms may 

 now be described. 



