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TEE POPULAR SCIENCE MONTELY.— SUPPLEMENT. 



all sensation and voluntary motion, as it is the 

 source of the nerves. And it is not argument 

 drawn from feeling that dictates his decision. 

 His opponents likened the dome of the skull to 

 that of the sky, and chose to fix the domain of 

 reason in the former, because the gods dwell in 

 the latter. Galen despises these arguments, as 

 lacking scientific value; he devotes himself to 

 experiments, and he made several very curious 

 ones, which are repeated at this day in the class- 

 rooms of the Museum and the College of France ; 

 he understands how to expose the brain of living 

 animals, he observes those parts of it that may 

 be removed without causing death, he practises 

 section of the marrow, and discovers the vital 

 knot ; he defines clearly the twofold action of the 

 nerves, he ties or cuts them, he sees that the 

 parts below the ligature lose at once all power of 

 motion or sensation, while above it no change 

 occurs. This is the great and earnest beginning 

 of researches that were neglected for thirteen 

 centuries after him, then resumed by Haller, and 

 are now pursued with daily-increasing eagerness. 



II. 



The nervous system of man comprises two 

 series of organs : the centres, represented by the 

 brain, the cerebellum, and the spinal cord ; and, 

 on the other hand, the nerves, radiating from 

 those centres throughout the body. The ancients 

 confounded these with the ligaments and tendons, 

 because all have the same pearly lustre. The 

 ligaments and tendons are merely bonds; the 

 nerves have a higher function : they put all the 

 points of our being in communication with the 

 centres, like an underground telegraphic network 

 in a city. We know, since the time of the fa- 

 mous microscopist, Leeuwenhoek, that they are 

 formed of very flexible filaments, united in bun- 

 dles of various sizes. These filaments, often called 

 tubes in consequence of an old error, are the es- 

 sential part of the nerve. We can give an idea 

 of their slenderness when we say that the diame- 

 ter of the largest is less than T gf 7 o of a line. Many 

 of them are only r £ 6 o or jfas of a line thick, and 

 even less. The smallest show in the field of the 

 best microscopes like mere cobwebs, without any 

 appreciable thickness. 



The outer structure of the nervous centres was 

 not ascertained till much later, in our own time. 

 It was simply known that the brain, the spinal 

 cord, and the cerebellum, are composed of two 

 substances differing much in appearance : one 

 gray, slightly pink, moderately transparent ; the 

 other shining, and of a dead white : both pulpy, 



and easily crushed under the finger, like soft pap. 

 Anatomists had almost confined themselves to 

 studying the volume, shape, and outlines, of these 

 parts, when a man famous for his exaggerated 

 doctrines, but one not to be too severely judged, 

 Dr. Gall, opened an entirely new path for the 

 anatomical and physiological study of the brain. 

 Gall, expelled from the University of Vienna as 

 a teacher of dangerous ideas, had passed through 

 Europe in a triumphal progress almost unexam- 

 pled in the history of scientific careers. Univer- 

 sities, learned bodies, municipalities, give him 

 welcome, and medals are struck in honor of him. 

 He arrives in Paris heralded by boundless renown, 

 and without delay presents a great memoir to the 

 Academy. It appoints a committee, in the name 

 of which Cuvier, a few days later, offers a report. 

 There were two things in Gall's paper : first, his 

 theory, well known to the world, and on which 

 Cuvier expresses no opinion ; and, next, another 

 part, wholly anatomical, with views upon the inner 

 structure of the brain, which Cuvier praised highly 

 in his report. Gall proved that the white sub- 

 stance is made up of an innumerable collection 

 of fibres, all having a certain and fixed direction, 

 in evident relation with definite functions, the 

 thorough understanding of which at once became 

 highly important. These fibres are all like those 

 that Leeuwenhoek had seen in the nerves, but 

 are of extreme softness. Those of the nerves 

 owe their firmness solely to the sheath which 

 guards them against the friction of the neighbor- 

 ing organs. The soft. fibres of the brain establish 

 communication between the different parts of the 

 gray matter, and consequently prove direct rela- 

 tions between those parts. To have demonstrated 

 this single point would have been enough for the 

 glory of Gall. He laid the solid basis on which 

 modern physiology was soon to begin building the 

 positive science of intelligence: the knowledge 

 of the inmost anatomy of the brain became the 

 necessary introduction to all psychological study. 

 Thus anatomists, particularly in Germany, en- 

 tered boldly upon the path traced out by Gall. 

 One of them, named Stilling, has written a quarto 

 volume, of a thousand compact pages, on the ar- 

 rangement of the fibres of the spinal cord. Were 

 the direction of the fibres of the brain to be de- 

 scribed as completely, it would require at least 

 twenty such volumes, and twenty single lives ; and, 

 until the completion of this enormous work, many 

 problems will, perhaps, remain insoluble. 



The assimilation of the filaments or tubes that 

 make up the white matter of the brain with those 

 of the nerves was a great point. The former 



