750 R. ROW. 
be found with high powers, but these are obviously separated 
from the colonies in the preparation of the smear. The 
masses consist of great numbers of parasites growing in 
colonies and entwined with one another. ‘The colonies may 
be compact and more or less spherical, in which case it is 
more difficult to make out the shape of the individual para- 
sites; or they may be looser in texture with the individuals 
more separate (fig. 4). 
The parasites have now increased in length to two and 
a half or three times the diameter of a red blood-corpuscle, 
and in breadth to about half or two-thirds this diameter. 
The shape of each individual is like a banana (fig. 4); the 
contour of the body is well defined, the sides being parallel 
and the ends rounded; the anterior extremity bearing the 
micronucleus is more rounded than the other. The parasites 
are not mobile or amoeboid, and for the most part no 
flagellum can be detected, though in some this organ is 
already present (fig. 5, a-c). The body-protoplasm shows a 
shehtly spongy character, and takes up a deeper stain than 
in younger forms. The macronucleus is centrally situated 
and is less compact than in young forms. The micronucleus 
has shifted to one end of the body and shows a faint sem- 
blance of a vacuole round it. 
At seventy-two hours the development is complete (fig. 6, 
a-)). The flagellum seems to be formed a few hours after 
the forty-eight-hour stage as an outgrowth from the micro- 
nucleus of a fine filament, which probably shoots out rapidly 
at the stage when the parasite may be supposed to have 
reached maturity. Once the fiagellum is formed, the 
individual is liberated and is free to swim away from the 
colony. Here and there groups of six or more fully developed 
flagellated individuals are found, entangled by their inter- 
twining’ flagella. 
The body of the parasite is practically the same as described 
at forty-eight hours, except that it has grown a httle longer 
and stouter, and the distinction between the posterior pointed 
and the anterior flagellate end is better marked. The flagel- 
