2 5 2 POPULAR SCIENCE MONTHLY. 



to the size of the animal. ... It is notorious that the instinct of 

 propagation, the instinct of destructiveness, the instinct of construct- 

 iveness, 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." f 



We have the following testimony in our favor from Dr. Rudolph 

 Wagner, of Gottingen: "Examples of highly complicated convolu- 

 tions 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 convolu- 

 tions." % 



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 con- 

 sists 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." tt 



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, 



* History of Philosophy, London, 1867, vol. ii, p. 433. 



f The Brain as an Organ of Mind, London, 1880, pp. 276, 277. 

 \ Nachrichten, Gottingen, February 29, 1860, p. 75. 



* Carpenter's Principles of Human Physiology, London, 1881, p. 659. 

 | Edinburgh Medical and Surgical Journal, 1853, vol. lxxix, p. 360. 



