Volume 1

Aphasia and kindred disorders of speech / by Henry Head.

  • Henry Head
Date:
1926
Catalogue details

Licence: In copyright

Credit: Aphasia and kindred disorders of speech / by Henry Head. Source: Wellcome Collection.

    22/576 (page 2)
    new theories on the functions of other organs. The soul, as the principle of life, was distributed to various parts of the body, and in conjunction with the crude substances it found there was distributed in three forms of “spirits.” The liver concocted from the food the “natural spirits,” whilst the heart was the centre of the “ vital spirits,” which rushed through the vessels of the body. In the same way the brain manufactured the “animal spirits,” according to Vesalius, out of the blood together with the air which entered through the ethmoid plate and other orifices of the skull. These animal spirits were distributed from the brain through all parts of the nervous system to form the basis of consciousness and volun¬ tary action. He said: Nerves1 serve the same purpose to the brain that the great artery does to the heart, and the vena cava to the liver, in as much as they convey to the instruments to which it ought to be sent the spirit prepared by the brain, and hence may be regarded as the busy attendants and messengers of the brain. He adds: Meanwhile we will not too anxiously discuss whether the spirit is carried along certain hollow channels of the nerves, as the vital spirit is carried by the arteries, or whether it passes through the solid material of the nerves, as light passes through the air. But in any case it is through the nerves that the influence of the brain is brought to bear on any part, so far as I can certainly follow out the functions of the brain by means of vivisections, with great probability and indeed truth. But how the brain performs its functions in imagination, in reasoning, in thinking and in memory (or in whatever way, following the dogmas of this or that man, you prefer to classify or name the several actions of the chief soul) I can form no opinion whatever. Nor do I think that anything more will be found out by anatomy or by the methods of those theologians who deny to brute animals all power of reasoning and indeed all the faculties belonging to what we call the chief soul. For as regards the structure of the brain, the monkey, dog, horse, cat, and all other quadrupeds which I have hitherto examined, and indeed all birds, and many kinds of fish, resemble man in almost every particular. Nor do we by dis¬ section come upon any difference which would indicate that the functions of those animals should be treated otherwise than those of man; unless perchance anyone says, and that rightly, that the mass of the brain attains its highest dimensions in man, which we know to be the most perfect animal, and that his brain is found to be bigger than that of three oxen; and then in proportion to the size of the body, first the ape, and next the dog exhibit a large brain, sug¬ gesting that animals excel in the size of their brains in proportion as they seem the 1 Translated by Michael Foster [49], p. 255 et seq.