24 UMBILICAL VESSELS. Secr.lll. ER

of them an abforbent fyftem of veflels, which imbibe the nutritious matters laid up for them in the ailbumen'‘or white ofthe egg, and in the cotyledons or lobes of the feed; and alfo of a placental{yftem of arteries for the purpofe ofoxygenatine their fluids, as defcribed above in the feed, and which appears in the eos to be fpread on a mem- brane, which covers the white, as is fhewnin the plates of Mal. pighi, and called by him the chorion, and expoles the blood of th

vga

chick to the ox gen of the air contained at the broad end of the eg throuoh a moift membrane.

4. The ufe of the large apparent artery fpread on the cotyledons of a germinatins feed of a garden-bean, called feminal roots by Grew, as fhewn in Plate I. Es, said that{pread on the chorion of the chick in the ego, fo called by Malpighi, and fhewn in Tom. Il. Fig. 54, and by Fabricius ab Aquapendente, Tab. I. Fig. 13, which muft be an artery, as it carries red blood, are behieved to be refpiratory organs, like the placental veflels of the fetus of viviparous animals, becaufe the cotyledons of fome feeds rife out of the ground, and be- come leaves, after the nutriment they contained is expended, and are then called feminal leaves, as in the kidney-bean, phafeolus; and becaufe thofe which do not rife out of the ground perifh beneath the {oil, as foon as the young plant gains its leaves, which are its acrial refpiratory organ.

Secondly, the chorion of the chick confifts of à membrane includ- ing the white, or albumen, and is not only in contact with the air-

bag at the broad end of the egg, which, as the chick advances, co-

vers more than half of the internal furface of the fhel, but alfo with

pal

| the membrane which lines all the other part of the fhell, as appear in Plate HT. which is copied from Malpighi: yet this exteufive

chorion; with the numerous arteries and veins which are{pread upon

Î

its furface, is not drawn up into the body of the chick like the volk and its including membrane, but perifhes at the nativity of the chick 4 1== ST:& n fa= æ Vorut AFNIICG A1 a Ç+ UE M a hke the placental veffels of the fetus of vis iparous animals; or fome-

CIMES,