N. H. SWELLENGREBEL AND C. STRICKLAND 
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less developed flagella. This is particularly clear in the Heidenhain 
preparations (Diagram VIII, Fig. 2). 
Diagram XI, Figs. 1 and 3 show a rosette with round and small 
oval forms. By continuous division rosettes are produced which are 
wholly composed of small oval forms (Diagram X, Fig. 2). 
The round forms, which may be found dividing when occurring 
singly or in rosettes, show distinctly the different stages of nuclear 
division (Diagram XI). Fig. 5 shows an elongated nucleus, slightly 
constricted in the middle with divided karyosome, the rest of the 
chromatin being situated in the periphery. In Fig. 6 the constriction 
is better marked, the peripheral chromatin has been retracted to the 
poles of the dividing nucleus. Fig. 5 shows also an interesting stage 
of the division of the blepharoplast. The chromatic portions at the 
two ends of the dividing organella are composed of a chromatic granule 
and a chromatic polar plate, which would suggest that the division of 
the blepharoplast is proceeding in the same way as the nucleus, the 
polar plate corresponding to the peripheral chromatin and the chromatic 
granule to the karyosome (centriole). However this may be, we saw 
such a figure only once, and we have no right to deduce any far- 
reaching conclusions from a single figure. The round forms contain 
many dark-staining granules. Generally they have no free flagellum 
but exceptions to this rule may be observed (Fig. 4). 
In the wet-fixed Heidenhain preparations the structure of the 
nucleus is the same as in the Giemsa preparations (Diagram X, 
Figs. 1, 3 and 4). A karyosome is generally present but sometimes 
only peripheral chromatin is to be seen (Figs. 1 and 4) as is also the 
case in the Giemsa preparations (Diagram XI, Fig. 4). The structure 
of the blepharoplast is often as clear as after staining by Giemsa, but 
the nuclear division is not so distinct, owing to the shrinkage of the 
nucleus which is often considerable (Fig. 3). As in Giemsa preparations 
a pale-staining substance may be seen uniting the round forms in a 
rosette (Fig. 1). 
The small oval forms arising from the division of the round forms 
have their blepharoplasts beside or in front of the nuclei (Diagram X, 
Fig. 2). At first the flagellum is only internal but grows out very soon 
(Figs. 5—6). As in the large oval and round forms there is often no 
flagellum to be seen in the small oval flagellates. We seriously doubt, 
however, whether the flagellum ever disappears, because none of the 
different types lacks a flagellum constantly ; it is always to be found 
in a certain percentage of the different types. It seems probable that 
Parasitology in 24 
