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from its triangular form, it always remains full. The aqueous 
liquid, by which the ventricles are filled, varying in quantity, 
answers the purpose of equalizing internal pressure. 
As the transparent mucus not only is one of the most abun- 
dant materials of which the brain itself is composed, but is 
the medium by which the globules of the retina are kept 
together, and serves the same purpose in the medullary tex- 
ture of the nerves, there can be no doubt that the communi- 
cation of sensation and volition, more or less, depend upon it. 
And it would appear from the following case, that when 
parts are regenerated, they contain a sufficient quantity of 
this mucus to connect them with the nerves of the body, and 
enable them to partake of its sensibility. 
A lady, who had a wound on the breast in a healing state, 
had a prominent spot of a black colour suddenly make its 
appearance on the surface ; it was very tender to the touch ; 
next day it disappeared, and the tenderness was gone. This 
must have been blood coagulated upon the termination of 
a nerve, and therefore the impression made by touching it 
was communicated along the nerve ; but when it was ab- 
sorbed, the bare nerve received a coating of coagulable 
lymph, and there was no more pain. 
Mr. Hunter's comprehensive mind grasped at the idea of 
the existence of something of this kind, although he had not 
arrived at a knowledge of the substance employed to produce 
the effect. He said, that so wonderful was the connection 
between the brain and every structure of the body, that it was 
to be explained in no other way than by considering, that the 
materia vitas was every where ; that it was in two forms col- 
lected into one mass in the brain, which he called coacervata; 
