W. M. Aders 
205 
is possible that their significance may have been mistaken. The young 
immature parasite is generally pear-shaped, and however formed is 
easily recognisable (Fig. 2, cl and e). Its nucleus stains pink and is 
situated at the rounder end of the parasite. The protoplasm stains blue 
and may appear somewhat vacuolated. When highly magnified indefinite 
chromosomes can be made out, but it is not possible to count them. 
In the young parasites the blepharoplast measures about ^ the size of 
the nucleus; it is almost always circular in shape and stains deep red. 
Owing to its great affinity for the stain no inner structure could be 
demonstrated. There was no other structure visible in these young 
forms. In the next stage the young parasite appears larger. Its form 
is elongated and the flagellum grows out from the micronucleus (Fig. 2, 
g and h). Division by longitudinal fission may now commence (Fig. 2, 
i and j). The parasites now rapidly become elongated until the adult 
stage is reached. 
A typical adult parasite (Fig. 2, l, m and n) measures about 18 gc in 
length and from 2 to 3 g in breadth at its widest part. Its posterior end is 
usually somewhat pointed, although I have seen a few with blunt ends. 
The body is cylindrical with a blunt anterior end. The protoplasm 
stains very evenly, there being no vacuolated areas. One unstained 
area is present around the blepharoplast. The nucleus is generally 
spherical in shape and is placed centrally, but occasionally it is situated 
behind. The nucleus shows great affinity for the red constituent of the 
Romanowsky stain, but in more or less decolourised preparations chromo¬ 
somes can be distinctly made out. The blepharoplast is more rod-shaped 
than round : it stains very darkly and is situated at the anterior portion 
of the flagellate. In many parasites it has a double appearance sug¬ 
gesting commencing division. The flagellum measures about 13 g in 
length ; it consists of one stout filament which arises from an achro¬ 
matic space somewhat anterior to the blepharoplast and passes out at 
the anterior end. The intracellular portion of the flagellum does not 
differ from the rest, and no basal granule could be detected. On 
examining a flagellate which is about to commence dividing (Fig. 2, q ) 
it can be seen that the nucleus is somewhat enlarged ; it does not stain 
so readily, and in some cases chromosomes are recognisable. The 
blepharoplast is thickened and somewhat elongated. It was not possible 
to ascertain if the second flagellum grew out of the micronucleus, or if 
it were formed by the splitting of the original flagellum. After close 
examination of many specimens it seems most probable that the new 
flagellum grows from the micronucleus (Fig. 2, q), at a later stage the 
