an animated similar part, composed of a body and a vital prin- ciple. When this living principle of the blood escapes, how- ever, in consequence of the extinction of the native heat, the primary substance is forthwith corrupted and resolved into the parts of which it Avas formerly composed ; first into cruor, after- wards with red and white parts, those of the red parts that are uppermost being more florid, those that are lowest being black. Of these parts, moreover, some are fibrous and tough, (and these are the uniting medium of the rest,) others icho- rous and serous, in which the mass of coagulum is wont to swim. Into such a serum does the blood almost wholly resolve itself at last. But these parts have no existence severally in living blood; it is in that only which has be- come corrupted and is resolved by death that they are en- countered.
Besides the constituents of the blood now indicated, there is yet another which is seen in the blood of the hotter and stronger animals, such as horses, oxen, and men also of ardent constitu- tion. This is seen in blood drawn from the body as it coagu- lates, in the upper part of the red mass, and bears a perfect resemblance to hartshorn -jelly, or mucilage, or thick white of egg. The vulgar believe this matter to be the pituita ; Aristotle designated it the crude and unconcocted portion of the blood.
I have observed that this part of the blood differs both from the others and from the mere serous portion in which the co- agulated clot is wont to swim in the basin, and also from the urine which percolates through the kidneys from the blood. Neither is it to be regarded as any more crude or colder por- tion of the blood, but rather, as I conceive, as a more spiritual part ; a conclusion to which I am moved by two motives : first, because it swims above the bright and florid portion commonly thought to be the arterial blood as if it were hotter and more highly charged with spirits, and takes possession of the highest place in the disintegration of the blood.
Secondly, in venesection, blood of this kind, which is mostly met with among men of warm temperament, strong and mus- cular, escapes in a longer stream and with greater force, as if pushed from a syringe, in the same way as we say that the spermatic fluid which is ejected vigorously and to a distance is both more fruitful and full of spirits.
