HIEUDO. 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 



