Page:Popular Science Monthly Volume 54.djvu/266

252 to the size of the animal. . . . It is notorious that the instinct of propagation, the instinct of destructiveness, the instinct of constructiveness, and other qualities are manifested by animals having no brains, nothing but simple ganglia."

Dr. Bastian demonstrates the convolutional theory thus: "In animals of the same group or order, the number and complexity of the convolutions increase with the size of the animal. . . . There can not, therefore, be among animals of the same order any simple or definite relation between the degree of intelligence of the creature and the number or disposition of its cerebral convolutions."

We have the following testimony in our favor from Dr. Rudolph Wagner, of Göttingen: "Examples of highly complicated convolutions I have never seen, even among eminent men whose brains I have examined. . . . Many convolutions and great brain weight often go together. Higher intelligence appears in both kinds of brains, where there are many or where there are few convolutions. It is not proved that special mental gifts go with many convolutions."

Another theory of mind is based on the gray matter of the brain, the amount of which has been supposed to be proportionate to mental capacity. As this gray matter, however, averages only about one fifth of an inch in thickness, it seems rather a thin foundation for the human intellect if the condition is good that "size is a measure of power."

The late Dr. W. B. Carpenter stated the matter thus: "The cortical substance or gray matter of the hemispheres essentially consists of that vesicular nerve substance which, in the spinal cord as in the ganglionic masses generally, is found to occupy the interior. The usual thickness is about one fifth of an inch; but considerable variations present themselves in this respect, as also in the depth of the convolutions."

Daniel Webster's brain had gray substance to the depth only of one sixteenth of an inch. It thus appears that his brain had a thinner layer of gray matter than the average of common-minded men—one among the many proofs that facts are against all theories that connect brain conditions with intellectual power.

Dr. Ireland thus describes an idiot boy who, though thirteen or fourteen years of age, was only three feet eight inches in height: "In expression he was dull and inanimate, with an old face and a short,