istence, man included. The dilemma for this conjecture that the brain thinks and wills is serious. If the brain is capable of what is commonly named mental activity, all that science has demonstrated is susceptibility and motor activity, that is nerve impulse involving molecular and muscular action, and this carries no explanation of mental action.

In this, as in previous cases, it is better to take purely scientific statements concerning the structure and functions of the nerve cells, without regard to theoretical result. The following quotations will show what account has been given of the variety of appearance and position of the nerve cells. Professor Turner says, nerve cells are "the characteristic structures in the nerve centres, are susceptible to impressions or nervous impulses, and are the texture in which the molecular changes occur that produce or disengage the special form of energy named nerve energy, the evolution of which is the distinctive mark of a nerve centre." The central extremities of the nerve fibres lie in relation to, and are often directly connected with the nerve cells." From opposite points of the surface of the bi

* Human Anatomy, i. p. 198.

polar cell "a strong process is given off, which is directly continued into a nerve fibre. * ” When we pass next to multipolar cells, we have the following explanations. "In many localities they present characteristic forms. In the gray matter of the spinal cord, more especially in its anterior horn,† they give rise to numerous processes, and have a stellate or radiate form. In the gray matter on the surface of the convolutions of the cerebrum they are pyramidal in shape; the apex is directed to the surface of the convolution, the base towards the white matter; the processes arise from the base, apex, and sides of the pyramid.” ‡ "The processes which arise from a multipolar nerve cell as a rule divide and subdivide as they pass away from the body of the cell, until at last they give rise to branches of extreme tenuity. These branching processes apparently consist exclusively of cell protoplasm, and have been called protoplasm processes. Gerlach has described the protoplasm processes of the multipolar nerve cells of the brain and spinal cord as forming an excessively minute net-work, from which mi

* Human Anatomy, i. p. 199.

From which motor nerves emerge. Human Anat., i. p. 200.

nute medullated nerve fibres arise."* "From the observations of Lockhart Clark, Arndt, Cleland and Meynert, there can be no doubt that the pyramidal nerve cells vary in relative size and in numbers in the different layers of the gray cortex, and that the largest sized pyramidal cells lie in the third and fourth layers."+ "Large pyramidal cells are found in the frontal lobe in considerable numbers," but it is added, "there is no difficulty in recognizing in the occipital lobe" (the back region of the brain) "a small proportion of cells quite equal in magnitude to the largest cells of the frontal lobe."‡

From these statements, it is easy to judge what value can be attached to the conjecture that multipolar or pyramidal cells are to be regarded as "mind-cells." The result may be summarized thus; (1) The larger cells are invariably distinguished by the number of fibres given off, or the lines of communication they have with other parts of the tissue; (2) As to distribution of these cell-fibres appearing in the brain, it is found that as the cells themselves are in the lower strata of the gray matter, the majority of their fibres stretch. * Human Anat., i. p. 201. ↑ Ib. p. 282. ‡ See Appendix XII.

downwards, the mass of the nerve fibres thus communicating with the organism; (3) These pyramidal cells are not peculiar to any part of the brain, and they do not belong to the brain alone, but are found in the gray matter of the spinal cord, and also of the sympathetic system, which provides for the action of the heart, lungs, and other vital organs. All these characteristics are adverse to the conjecture that for the larger sized cells a claim can be made assigning to them distinctively intellectual or mental functions.

In contrast with this view, I shall here introduce an extract from Hæckel's Evolution of Man, as he may be accounted the most advanced advocate of the theory of “mindcells." He says, "The nerve cell of the brain is an extremely one-sided formation. It can not, like the egg-cell, develop from itself numerous generations of cells, of which some transform themselves into skin-cells, some into flesh-cells, and others into bonecells, etc. But instead, the nerve-cell, which is formed for the highest activities of life, possesses the capacity to feel, to will, to think. It is a true mind-cell, an elementary

organ of mental activity. Correspondingly, it has an extremely complex minute structure. Innumerable filaments of exceeding fineness, which may be compared to the numerous electric wires of a great central telegraph station, traverse (crossing each other again and again), the finely granulated protoplasm of the nerve-cell, and pass into branched processes, which proceed from this mind-cell, and connect with other nerve-cells and nervefibres. It is scarcely possible to trace, even approximately, the tangled paths of these filaments in the fine substance of the protoplasmic body. We thus have before us a highly complex apparatus, the more minute structure of which we have hardly begun to know, even with the help of our strongest microscope, and the significance of which we rather guess than know. Its complex mechanism is capable of the most intricate physical functions. But even this elementary organ of mental activity, of which there are thousands in our brain, is only a single cell. Our whole intellectual life is but the sum of the results of all such nerve-cells, or mindcells."*

*Evolution of Man, i. p. 129.