FURTHER OBSERVATIONS ON C^CAL PARASITES OE FOWLS. 65 
pharynx is well developed, hut there is as yet no sign of the 
outgrowth of new flagella. It is possible that the pointed 
form (PI. 10, fig. 2) represents an individual which has just 
undergone division. 
Ency station. — The earliest stage of encystation that 
we have found is shown on PI. 10, fig. 7. The form here 
figured still preserves the rounded shape characteristic of the 
active individual, but the flagella have disappeared, and the 
pharynx is still well developed. 
In the next stage (PI. 10, fig. 8) the animal has become much 
smaller, and at the same time more oval, and a delicate wall 
has been secreted from its periphery. The remains of the 
blepharoplast are no longer to be detected, but it has possibly 
been absorbed into the nucleus, which has now passed from 
its former anterior to a more central position. 
In the next stage the cyst has practically assumed its 
definite shape. The nucleus has undergone a good deal of 
shrinkage, leading up to the solid, darkly staining mass seen 
in the ripe cy r st (PI. 10, fig. 10). The changes undergone in 
the pharynx during this process are rather ditficult to under- 
stand. It seems probable that, at any rate in the majority of 
cases, the thickened lining of the cytostome becomes 
loosened, and springing out of its original curved shape, lies 
as a darkly staining line running down one side of the cyst. 
A darkly staining cap at the anterior pole of the ripe cyst is 
due to a local differentiation of the cyst-wall. The whole of 
this process of encystation takes place in the cascum, and 
ripe cysts have been found in the faeces some time after 
deposition. No trace of a sexual process has yet been found 
in this cycle. 
In connection with this form we should like to draw 
attention to what is apparently a closely allied species, which 
was found by one of us to be very common in the rectum of 
the Saithe, Gad us virens, at Millport. It agrees closely 
with Chilomastix gallinarum, except for the fact that 
the terminal point is far more developed. We figure this 
animal in the second part of the paper. 
