NEW TYPE OF FlIOTtSTAN PARASITE. 
445 
but crescents whicli do not possess a flagellum certainly occur 
(figs. 36, 37). We are inclined to think that such forms 
may become ovals, which we have next to consider. 
The Ovals. — In their general appearance the ovals 
resemble the crescents. Their average size also is quite 
comparable ; they are somewhat shorter, but distinctly more 
bulky. Some of them are seen to be considerably elongated, 
but these are individuals either about to divide or in the act 
of dividing. Apart from their shape the essential point of 
difference from the crescents is that the ovals entirely lack 
the characteristic flagellum. Nevertheless the ovals are 
undoubtedly capable of movement, and this fact ^vas brought 
home to us in a surprising manner. When the fourth goat 
was examined for the first time an enormous number of active 
ovals were found, while the crescents Avere extremely scanty 
— far fewer in number than on any other occasion. The 
great majority of the ovals were in motion, the movement being 
one of progression, in a slightly zig-zag manner, but no sudden 
reversal of the direction of movement was noticed. At each 
of the subsequent examinations of the same goat, when the 
ovals have been relatively fewer and the crescents more 
numerous, most of the ovals have been quite still (although 
there Avere active crescents in the same preparations). Here 
and there, hoAvever, an oval would be seen zig-zagging to 
and fro slightly and spasmodically, scarcely progressing at 
all. And this has been the case in most of the other goats 
examined ; nearly all the ovals Avere motionless. We have 
not observed any rotation of the ovals on their own axis, 
such as is commonly seen in the crescents. The remarkable 
activity of the ovals on the particular occasion referred to 
soon subsided, and after about a couple of hours they Avere 
all still. In the last goat examined, however, many of the 
ovals, as Avell as the crescents, were active, and Ave Avere able 
to observe a distinct indication of antero-posterior polarity in 
their case also. Noav and again an oval steadily progressing 
Avould come aofainst an obstacle. When this occurred the 
oval did not move aAvay in the opposite sense, but turned 
