HIRUDO. 17 



corresponding axis of any cylindrical substance, whereon the capsule is 

 deposited for example a bulrush. Its position is frequently oblique, on 

 substances of greater diameter. A red speck is readily seen at each ex- 

 tremity of those of lighter colour. 



Some of the capsules are found vacant, and thence abortive in pro- 

 duction. Others contain from one to twelve minute white specks, the 

 elements of as many future embryos. Figs. 5, 6, 7, 8, 9, capsules after 

 nature ; figs. 10, 11, enlarged. 



The embryos are scarcely perceptible by the naked eye, and are dis- 

 persed like grains irregularly in the capsule. None are evidently con- 

 fined by any peculiar involucrum ; nor are they arranged in any definite 

 or reciprocal position. The form of the advancing embryo is so irregular 

 as to occupy in appearance a great portion of the capsule. Figs. 12, 

 13, 14, 16. If several embryos occur in the same capsule, there is scarcely 

 room for their growth. The young leech at length escapes in proper season. 



In a vessel containing two leeches, two capsules were deposited on 

 August 27. Ten single specks seemed to be included in one of them, 

 and apparently seven pairs, together with a single speck, in the other. 

 The contents of the latter had, to my apprehension, resolved into single 

 specks in a few days. But the capsule proved wholly abortive ultimately. 



On the 1st or 2d of September six or seven of the ten in the other 

 capsule were enlarged, as if inflated ; and on the 13th of the month, six 

 or seven pale, dingy leeches, ranged together longitudinally, were dis- 

 covered occupying the capsule in common. Observation had been in- 

 terrupted during the interval. The motion of these animals, sensible on 

 the 14th, became gradually more evident on the 21st, when the body 

 was curving and extending. Finally five of them escaped through one 

 of the red spots above mentioned, on the 29th, though apparent ma- 

 turity prognosticated an earlier exit. Two still within the capsule some- 

 times advanced from below, as if irresolute whether to attempt the same 

 means of liberation. One adventured on it next day, and the other on 

 that following. 



Thus thirty- one or thirty-two days had intervened between deposi- 

 tation of the capsule and the maturity of its contents. 



C 



