211 
(phaseolus) ; so the white corol of the helleborus niger, (christmas rose) is 
changed into a green calyx by losing one system of arteries after the im¬ 
pregnation of the seeds. 
The seed-embryo therefore resembles the chick in the egg, first as 
when vivified by the influence of external warmth they both begin their 
growth by the absorbent system of vessels being stimulated into action by 
their adapted nutriment; and the fluids thus pushed forwards stimulate into 
action the other parts of the system, consisting at first principally of arteries 
and glands. 
First, they seem much to resemble each other in their possessing each of 
them an absorbent system of vessels, which imbibe the nutritious matters 
laid up for them in the albumen or white of the egg, and in the cotyledons 
or lobes of the seed; and also of a placental system of arteries for the pur¬ 
pose of oxygenating their fluids, as described above in the seed, and which 
appears in the egg to be spread on a membrane which covers the white, as 
is shewn in the plates of Malpighi, and called by him the chorion, and ex¬ 
poses the blood of the chick to the oxygen of the air contained at the broad 
end of the egg through a moist membrane. 
The use of the large apparent artery spread on the cotyledons of a ger¬ 
minating seed of a garden-bean, called seminal roots by Grew, as shewn in 
Plate I. fig. 1, and that spread on the chorion of the chick in the egg, so 
called by Malpighi, and shewn in tom. ii. fig. 54, and by Fabricius ab 
Aquapendente, tab. i. fig. 13, which must be an artery, as it carries red 
blood, are believed to be respiratory organs, like the placental vessels of the 
foetus of viviparous animals, because the cotyledons of some seeds rise out 
of the ground, and become leaves, after the nutriment they contained is 
expended, and are then called seminal leaves, as in the kidney-bean, (pha¬ 
seolus) ; and because those which do not rise out of the ground perish beneath 
the soil as soon as the young plant gains its leaves, which are its aerial 
respiratory organs. 
Secondly, the chorion of the chick consists of a membrane including 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, covers more than half of the 
internal surface of the shell, but also with the membrane which lines all the 
other part of the shell, as appears in our plate, which is copied from Mal¬ 
pighi : yet this extensive chorion, with the numerous arteries and veins 
which are spread upon its surface, is not drawn up into the body of the 
chick like the yolk and its including membrane, but perishes at the nativity 
