relation between the nervous and sanguiferous systems. 443 
foot, and the fins of fishes, without perceiving the least ten- 
dency to this irregular motion when the part viewed was so 
applied to the microscope as not to compress any of its vessels.* 
The power of the blood vessels, like that of the heart, is 
capable of being directly destroyed through the medium of 
the nervous system. 
j Exp. 17. The web of one of the hind legs of a frog was 
brought into the field of the microscope, and while Mr. 
Hastings, who was good enough to assist me in this and the 
14th experiment, observed the circulation, which was vigor- 
ous, I crushed the brain by the blow of a hammer. The 
vessels of the web instantly lost their power, the circulation 
ceasing. In a short time the blood again began to move, but 
with less force. This experiment was repeated with the 
same result. If the brain is not completely crushed, the 
blow increases the rapidity of the circulation in the web. 
Exp. 18. The spine of a frog was laid open at the lower 
end, and a wire of nearly the same dimensions with its cavity, 
forced through it, as in M. le Gallois's experiments. The 
web of one of the hind legs was then brought into the field 
of the microscope, and the circulation in it was found to have 
wholly ceased. In another frog, as we have seen,-f the spinal 
marrow was destroyed by the introduction, in the same way, 
of a wire much smaller than the cavity of the spine, and by 
its being moved in various directions. The frog soon appeared 
* An account of these experiments is published in the introduction to the second 
part of my Treatise on Febrile Diseases, and a plate given representing the state of 
the vessels in the different stages of inflammation. 
+ See Experiment 1. 
3 L 2 
