Page:The Works of William Harvey (part 1 of 2).djvu/585

 tends into either cornu ; the amnion swimming in the midst of the liquid of the former, is found in one of the horns only, except in the cases where there is a twin conception, when there is an amnion present in each of them ; just as in a twin-fraught egg there are two colliquaments. Where there are two foetuses consequently, both are contained in one common conception, in one egg, as it were, with its two separate collections of crys- talline fluid included. If you incise the external membrane at any point, the more turbid fluid which it contains imme- diately escapes from either horn of the uterus ; but the crys- talline liquid in the interior of the amnion does not escape at the same time unless the membrane have been simultaneously implicated.

The vein which is first discerned in the crystalline fluid within the amnion takes its rise from the punctum saliens, and assumes the nature and duty of an umbilical vessel ; increasing by de- grees it expands into various ramifications distributed through the colliquament, so that it seems certain that the nourishment is in the first instance derived from the colliquament alone in which the foetus swims.

I have exhibited this point to his serene highness the king, still palpitating in the uterus laid open ; it was extremely minute indeed, and without the advantage of the sun's light falling upon it from the side, its tremulous motions were not to be perceived.

When the ovum with the colliquament entire was placed in a silver or pewter basin filled with tepid water, the punctum saliens became beautifully distinct to the spectators. In the course of the next ensuing days, a mucilage or jelly, like a tiny worm, and having the shape of a maggot, is found to be added; this is the rudiment of the future body. It is divided into two parts, one of which is the head, the other the trunk, precisely in the same way as we have already seen it in the generation of the chick in ovo. The spine, like a keel, is somewhat bent; the head is indifferently made up of three small vesicles or globules, and swimming in transparent water grows amain, and by degrees assumes its proper shape. There is only this to be observed, that the eye in embryos of oviparous animals is much larger and more conspicuous than that of viviparous animals.

After the 26th of November the foetus is seen with its body