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General Principles of Physiology. 101 
around the umbilical cord. But we have no reason to believe 
that the secondary change effected in the blood of the foetus by 
the vicinity of the maternal blood of the placenta, (although this 
gives it the florid colour, as may be seen by opening the vessels of 
the chord,) is sufficient for the functions of the perfect animal. 
One of these functions, which we have just seen, we have reason 
to believe from many phenomena, as well as from direct experi- 
ments, to be intimately connected with the change effected on 
the blood by the air, the maintenance of the due temperature, it 
is evident, is immediately after birth required to be in astate of 
much greater activity than in the foetus, whichis surrounded by a 
medium of its own temperature. 
When respiration ceases, most of the pulmonary vessels, 
and left side of the heart, are no longer supplied with their pro- 
per stimulus, and feel more directly, perhaps, the debilitating in- 
fluence of black blood*. Their functions, therefore, begin to 
fail, and in proportion as this happens the blood accumulates in 
the lungs, and the right side of the heart consequently experiences 
* Biclat has been at great pains to ascertain the effects of black blood 
on the lungs, and other organs. To his experiments I refer the reader. 
There are but few parts of the physiological works of Bichat which can be 
confidently referred to. In general he has allowed his reasonings to go far 
beyond the evidence afforded by his observations and experiments. I shall 
take this opportunity of making a few remarks relating to the principal 
points in which I have differed from him. He was unacquainted with the 
fact, that the spinal marrow can perform its functions independently of the 
brain, and therefore did not see the difficulty respecting respiration stated 
by M. le Gallois, but seems to think that the division of the spinal marrow 
near the head occasions death by preventing the nervous influence of the 
brain from reaching the intercostal muscles and diaphragm. 'The want of 
this knowledge leads him into inaccuracies, both in his observations on 
death, and other passages ; which are increased by his not being aware that 
the sensorial and nervous powers have no direct dependence on each other. 
He is led into more obvious errors, as far as I am capable of judging, in 
various parts of his works, particularly in those which relate to the passions 
and the death of the brain, by his not knowing that the heart and blood 
vessels may be directly influenced, and even their power directly destroyed 
by agents acting either on the brain or spinal marrow; and by his suppos- 
ing that the ganglious are capable of preparing nervous influence indepen- 
dently of the brain and spinal marrow, a supposition which we have seen 
H 2 
