HIRUDO. 19 
shall be elicited. Here the regular advance is completely disclosed by 
the transparence of the capsular integument. It is seen that life may 
subsist a considerable time ; that the component parts may be greatly 
enlarged or refined before the attainment of such vigour by the em- 
bryo as enables it to demonstrate its own animation. Several days 
before the young leech adventures to escape, the eyes have become 
visible, a pair on each side, being situated at some distance behind the 
lunate series of four in front. Transparence of the capsule also exposes 
the great disparity of the brood, and that it is in every possible arrange- 
ment: farther, that the relative position of the young is altered, and 
that they traverse their prison in all directions previous to seeking an- 
other abode. 
Several capsules are produced by the same parent, both prolific and 
abortive, and in various numbers, independently of which the embryos 
are also contained in various numbers. It is difficult, however, to attain 
accuracy, as the production of some capsules may precede the selection 
of specimens of the leeches for observation. One specimen, taken July 
26th, produced four capsules from the 29th of that month until the 8th 
of August. The third was vacant of specks ; the first, second, and fourth 
contained eight, six, and five respectively. Another, taken August 19th, 
produced the last of five capsules on the 25th of September. Each of 
the first two contained ten embryos, the third eight, and the fourth seven. 
The fifth proved abortive. Thirty-five young, therefore, had come from 
the same parent. 
Where there are several embryos, some are generally abortive ; but 
there is no definite proportion in this condition. 
At first the capsule is almost transparent ; and, it may seem singular, 
that there are no previous sensible indications of its presence in the body 
of so small an animal as the eight-eyed leech. Its actual production is 
rarely to be witnessed. 
Some’ days after several specimens had been taken, it was observed 
that one of them, affixed by the sucker, exhibited an enlargement of the 
body, at about a third of the length from the anterior extremity. It con- 
tinued twisting itself very slowly, in such a manner that sometimes the 
