434 
H. M. WOODCOCK AXD G. LAPAGE. 
in tlie reticulum, and a few have been seen in the true 
stomach, but they have never been observed in the intestine, 
ctecum or rectum. In the last-named region of the alimentary 
canal, cysts and spores of one kind and another occur, the 
determination of which is a very puzzling matter, and it is 
quite possible that some one of these represents a resistant 
phase of the parasites ; but we have not succeeded in recog- 
nising anything corresponding to the characteristic ovals. 
Certainly no crescents are to be found, nor have they 
developed in any of the many cultures which we have made 
from the fteces, both of goats which we know to have been 
infected and of others which in all likelihood also were. In 
this feature Selenomastix agrees with the Ciliates and the 
ordinary Flagellates which occur in an active phase in the 
rumen. Like these, further, this new parasite appears to be 
purely an inhabitant of the fluid contents of the rumen. Vs e 
have carefully examined the wall, both externally and inter- 
nally, for any indication of cysts, large or small, but none have 
been visible. (Xone of the goats examined have shown any 
signs of the cysts of Gilruth.'^) 
IVe will first describe the appearance, behaviour and 
structure of the crescents, and can then readily compare the 
corresponding features in the ovals. Seen living and freshly 
removed from the rumen, either with or without the addition 
of a small drop of water or normal saline, all the crescents 
have a very similar and characteristic appearance, but show 
a considerable range of variation in size. The body has a 
uniform, homogeneous, dull-looking appearance. IVe have 
never observed the crescents alter in shape at all ; they 
are certainly not amoeboid or metabolic,^' and we have never 
seen them assume an S-shaped form, as mentioned by Certes 
(cf. below, p. 439). Many, if not most, of the crescents 
possess a definite envelope, as is seen from stained prepara- 
tions, but it does not stand out at all in life (contrast the 
ovals, below). Xo granules of any kind, or vacuoles, are 
noticeable in the protoplasm. 
If examined as soon as possible after removal from the 
