17 
on the Hirudo vulgaris. 
of a film or membrane, into which the animal forces, with 
some effort, the whole contents of the uterus. This done, the 
H. vulgaris elongates the anterior portion of the body, and 
thus loosening the enveloping membrane, withdraws its head 
from it, as from a collar. In some instances, where this 
membrane cannot be readily detached, I have observed the 
animal to bend back its head, and then taking it in its mouth, 
and drawing it gently, is thus enabled to remove it. From the 
first formation of this membrane or capsule, to its removal 
from the body, twenty minutes usually elapse. It is, at this 
time, very elastic, and of no determinate figure. After the 
H. vulgaris has firmly fixed it to some surrounding sub- 
stance, it fashions it with its mouth, until it presents an oval 
form, such as is delineated in Fig. 7. It afterwards returns 
once or twice to survey it, when all farther notice of it 
ceases. 
The accuracy of this statement may perhaps be questioned. 
It may be considered as highly improbable, that the capsule 
should be deposited after this manner. Strange, however, as 
it may appear, I have several times witnessed the leech 
drawing the anterior part of its body through it, as through a 
ring. Indeed, I know of no other way in which it can possibly 
get rid of it, the membrane forming a complete band round its body. 
Although this mode may be somewhat singular, yet there is 
little in it to excite our surprise, in comparison with what 
we find recorded in the works of naturalists. 
When deposited in an unattached state, that is, left free, 
and floating in the water, the capsules are mostly of a glo- 
bular form (as in Fig. 6 ). When fixed to any substance, they 
present an oval form ( as in Fig. 7), which is, by far the most 
MDCCCXVI I* D 
