NATURAL HISTORY OF BRITISH FRESH-WATER LEECHES. 69 
is satisfied that the cocoon is firmly fixed, it withdraws the 
body in the following manner. A wave of dilation passes for¬ 
ward along the body, enlarging the posterior orifice of the cocoon, 
which is thereby detached at its hinder part. The fore part 
of the body is then drawn backwards, but instead of simply 
passing out of the sheath, it brings the two extremities of the 
cocoon into contact, by a process of invagination. The body is 
withdrawn and in less than a minute the cocoon assumes its 
natural egg-like shape without the help of the leech. In the 
case of Herpobdella the animal presses down the margins with 
the aid of the anterior sucker and fixes the edges by means of a 
secretion. This produces the oval, dome-shaped cocoon 
characteristic of this species, in which the apertures through 
which the body has passed may be seen in the form of two 
dots—one near each end of the cocoon. Brumpt goes on to 
say : At the moment when the cocoon is deposited the anterior 
part of the body, contaminated with bacteria, infusoria and a 
number of other impurities, is not brought into contact with 
the contents of the cocoon. It would seem that a paradoxial 
problem had been solved, viz., to pass through an albuminous 
mass without touching it. The cocoon is deposited with due 
regard to aseptic precautions. 
All the members of the Sub-order Arhynchobdellse deposit 
cocoons which receive no further attention from the animal. 
The same statement, of course, applies to Piscicola geometra, 
described above. A group of leeches forming the Family Glossosi- 
phonidae carry the eggs on the under side of the body in some 
cases, and in others the eggs, though deposited on foreign bodies, 
are brooded over by their parents. The young when hatched 
attach themselves to the body of the parent and are carried 
about for some time. A primitive maternal instinct seems 
to have been developed in some instances. A specimen of 
Protoclepsis tessellata, taken by the writer, laid 36 eggs on the 
side of a glass tank and brooded over them. When prodded 
with a pen holder, the mother struck out viciously. Unfor¬ 
tunately the eggs never hatched, but some months afterwards 
three small specimens of the same species were placed in the 
lank with the adult. Two of them immediately attached 
themselves to the underside of “ her ” body. The third, which 
was a little larger, refused to seek protection of a foster-parent. 
