The essentials of psychology / by W.B. Pillsbury.

  • Pillsbury, W. B. (Walter Bowers), 1872-1960.
Date:
1911
Catalogue details

Licence: In copyright

Credit: The essentials of psychology / by W.B. Pillsbury. Source: Wellcome Collection.

    36/392 (page 20)
    that has lost something of its individuality, but is never- theless descended directly from the independent amoeba- like prototype. The bone cells perhaps are most removed from the original; the corpuscles of the blood, the white corpuscles in particular, have changed hardly at all. Next to the blood corpuscles the nerve-cells probably have been least changed from the original type. Except for its dependence upon the other members of the colony for its food, and for the fact that the other cells serve to give it form, a nerve-cell is still independent. The function of the nerve-cells in the colony may be regarded metaphori- cally as protective and connective. They compel the different parts to act together, and on the right occasion they enable the parts to respond to the external world. The nervous system enables the organism to act as a unit and not as a mass of separate organisms. The Divisions of the Nervous System. —As one looks at the central nervous system of man, one can observe three fairly distinct structures. The largest is the cere- brum, enclosed by the skull. This is a mass roughly like a sphere much corrugated on its surface by irregular folds. Two of the fissures are most prominent. One, the median fissure, serves to divide the cerebrum into two parts throughout more than half its height. It is in the approximate centre of the mass. This division makes it customary to regard the halves as distinct, and hence we speak of the two hemispheres. The other is on either side of the hemispheres, is not so deep, and is known as the fissure of Sylvius. Slanting upward from the lower front part of the brain, it will be seen from the diagram to con- stitute a prominent landmark. Below the cerebrum at