336 
situated at, or very near, the posterior extremity, and by a dear space 
about the nucleus. The blepharoplast apparently consisted of four 
darkly-staining granules of equal size embedded in a matrix. In a 
few specimens there were, perhaps, more than four granules in the 
blepharoplast, but in these cases it was never possible to be certain 
of the exact number. The three forms of parasites seemed but 
different variations of one species, as gradations between all forms 
could be seen. 
The small type was readily distinguished by its size, its narrow 
body, its relatively long nucleus situated more anteriorly than in 
the other two types, and with its long diameter parallel to that of the 
body—and by its faint-staining reaction. The blepharoplast was 
oval, or round, large and distinct (measuring 113 by 075/*). and was 
situated at the posterior extremity. The undulating membrane was 
well developed, having a width of 075 /*. The long, oval nucleus 
was situated at the junction of the middle and anterior thirds of the 
body. It was granular in structure and contained a fibrous network 
on which were seen eight to sixteen chromatin granules, and one 
darker granule—the karyosome. The body protoplasm was 
reticular, and contained a few violet-staining granules. Occasionally 
parasites were seen in which the body was filled with these coarse 
chromatophilic granules. Superficial longitudinal striations to the 
number of five could be seen near the nucleus of two slightly injured 
parasites. Division forms were very numerous in this type (even 
when but four were seen in the fish of December gth, one of them 
was dividing). I hey followed the usual method of longitudinal 
division. In the division of the blepharoplast, the posterior lobe on 
the concave side of the parasite moved behind the other postenor 
lobe ; the axis of the posterior lobes thus became longitudinal, while 
that of the anterior lobes remained transverse. The two posterior 
lobes then separated from the anterior lobes and their axis became 
transverse again. 
The medium type was characterised by its size, and its darker 
staining reaction. The blepharoplast was large, oval or round, 
distinct and measured about 1-5 by 075 /x. It was situated at the 
posterior extremity, or from 1 to 1*5// anterior to it. The flagellum 
was re l a tively longer than in the short form. The undulating 
membrane in parasites from the fish of December 30th was well 
