2GS 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



white matter composing half of it is henceforth 

 known to us. Its function is merely to transmit 

 from one point of the brain to another those ex- 

 citements of which the origin is yet to be sought, 

 while their nature is determined wholly by that 

 of the apparatus which receives them. We may 

 add that this receiving apparatus is always a 

 mass of gray matter, which, therefore, is the im- 

 portant part into the function of which we must 

 inquire. 



The gray matter is not a formless jelly, any 

 more than the white. It has an organization, 

 being made up of little bodies called by anato- 

 mists cells, provided at the centre with a kernel, 

 resembling in shape a microscopic egg. This 

 cell sends out on different sides a great number 

 of prolongations, which split up, branch out, and 

 cross each other, in all directions. Some become 

 so slender as at last almost to elude observation ; 

 others continue themselves into the soft tubes 

 of the white matter, and this union attests even 

 more clearly, if that is possible, the correctness 

 of Gall's announcement, that the first point was 

 to gain a thorough knowledge of the connections 

 linking together the different masses of this gray 

 matter, in which, by a sort of intuition, unfortu- 

 nately too rash in its deductions, he had mapped 

 out our faculties, our aptitudes, and our various 

 sentiments. The gray matter is most truly the 

 very door of the nervous system. It is, so long 

 as it continues living, the seat of intelligence, 

 of all knowledge and all consciousness, as well 

 as of the passions that agitate and the illusions 

 that lull us. The wisdom of the world, and its 

 most violent extravagances, all issue from it ; it is 

 the region in which thoughts germinate, schemes 

 unfold, the future is built. All psychology is but 

 the study of the functions of the gray matter; 

 but while the old philosophies admitted scarcely 

 a gap in their conceptions, and all gave us a 

 finished theory of intelligence, biologists, it must 

 be confessed, are far from being as advanced. At 

 most, they have hitherto been able only to grasp 

 some scattered shreds of the whole, some isolated 

 links in an inextricable web. Yet, in truth, the 

 results that have crowned their labors are not 

 such as to discourage inquiry, and we might rath- 

 er wonder at the conquests achieved, so abun- 

 dant are they in promise and in hope for coming 



progress. 



in. 



The only method to escape being lost in any 

 scientific investigation, whether it bears upon the 

 material world or upon that of our consciousness, 

 is to advance from the known to the unknown. 



A science is founded so soon as a fact, whatever 

 it may be, is well settled. It forms a point whence 

 we set out on new discoveries, until another and 

 a broader one has been found. Now, one fact 

 strikes us at once in the study of the intellect, 

 and that an indisputable one : it is very certain 

 that the feeling we have of the outer world, the 

 group of our perceptions, to use the language of 

 physiology, is distinct from that outer world, 

 since that is external to us, and perceptions are 

 in us. Heat thrown off by a fire evidently has 

 the same action on our hand as on any other 

 body, but the sensation we experience is clearly 

 different ; it is no longer caloric. It is said that 

 we see the world through our organs ; and that 

 is true, in this sense, that they show us a world 

 quite different from what it is in reality. It is 

 certain that they give us a translation of it with- 

 out our having the power, in many cases, to de- 

 tect in what it is incomplete or inexact. The 

 world, such as we see it, is in ourselves, not mere- 

 ly distinct from the reality, but up to a certain 

 point purely imaginary, the creation of our ner- 

 vous system. An example will illustrate the dif- 

 ference : A tense string vibrates ; whether the 

 vibrations are rapid or not, the hand brought 

 near the string feels it oscillate very plainly. If 

 the number of vibrations in a second is not very 

 great, say about fifteen, only the touch is affected, 

 and it gives the sensation of the string's motions. 

 We may allow that in this case our inner sense 

 gets the faithful translation of the material fact 

 of which the string is the seat ; but, let the num- 

 ber of vibrations increase, and we suddenly feel 

 a new and wholly different sensation, which is 

 added to the former one, and in a manner gov- 

 erns it. The finger on the string continues to 

 feel its vibrations, but these, conveyed to the ear, 

 there produce an entirely different effect — a sound. 

 And yet the ear has been physically agitated by 

 the movements of the air, as the fingers are by 

 those of the string ; the impressions on the or- 

 gans are of the same order, the sensation differs. 

 If the former is the exact translation of that which 

 is passing outside of us, the latter exists wholly 

 in us, and has no reality ; a mechanical movement 

 gathered up by the ear becomes a sonorous per- 

 ception. Here is one of those transformations 

 of motion that must be added to those which 

 physics are studying so earnestly. There is a 

 nerve equivalent of motion, as there is a me- 

 chanical equivalent of heat. We see all the im- 

 portance of this great physiological fact, which 

 thus links the inmost perceptions of the me to 

 the great laws of the physical world. This trans- 



