September 2, 1897] 



NATURE 



433 



apparently of intellectual improvement beyond their present low 

 state of development. In thirty-nine men the mean cajiacity 

 was only 1280 c c. (78"i cub. in.). The maximum capacity 

 was 1514 c.c, the minimum was 1044 c.c. The range of 

 variation was 470 c.c. In twenty-four women the mean capacity 

 wasill5'6 c.c. , the maximum l)eing 1240 and the minimum 

 930, and the range of variation was 310 c.c. It is noticeable 

 that in this series of sixty-three Australian skulls, all of which 

 are in the Anatomical Museum of the University of Edinburgh, 

 eight men had a smaller capacity than 1200 c c, and only four 

 were above 1400 c.c. Of the women's skulls ten Mere below 

 1 100 c.c, four of which were between 900 and 1000 c.c, and 

 only three were 1200 c.c. and upwards. 



Time does not admit of further detail on the cranial capacities 

 of other races of men. Sufficient has been said to show the 

 wide range which prevails, from the maximum in the Europeans 

 to the minimum in the Australians, and that amongst persons 

 presumably sane and capable of discharging their duties in their 

 respective spheres of activity ; for we must assume that the 

 crania of the Australians, having the small capacities just referred 

 to, were yet sufficiently large for the lodgment of brains com- 

 petent to perform the functions demanded by the life of a savage. 

 From a large number of measurements of capacity which I have 

 made of the skulls of the principal racps of men, I would draw 

 the following conclusions : First, that the average cranial 

 capacity, and consequently the volume and weight of the brain, 

 are markedly higher in the civilised European than in the 

 savage races ; second, that the range of variation is greater in 

 the former than in the latter ; third, that in uncivilised man the 

 ]:)roportion of male crania having a capacity equal to the 

 European mean, 1500 c.c, is extremely small; fourth, that 

 though the capacity of the men's skulls is greater than that of 

 the women's, there is not quite the same amount of difference 

 between the sexes in a savage as in a civilised race. 



It may now be of interest to say a few words on the capacity 

 of the cranium in the large Anthropoid apes. I have measured, 

 by the method already referred to, the capacity of the skulls 

 of five adult male Gorillas, and obtained a mean of 494 c.c, 

 the maximum being 590 c.c. and the minimum 410 c.c, the 

 range of variation being 180 c.c. Dr. Delisle found the old 

 male Orang (Maurice),' which died a short time ago in the 

 Jardin des Plantes, to have a capacity of 385 c.c, whilst the 

 younger male (Max) had a capacity of 470 c.c- The mean of 

 eleven specimens measured by him was 408 c.c, which is some- 

 what less than the measurements of males recorded by M. 

 Topinard and Dr. Vogt ;.but it should be stated that in some 

 of Dr. Delisle's specimens the sex could not be properly dis- 

 criminated, and possibly some of them may have been females. 

 The cranial capacity of seven male Chimpanzees is stated by 

 M. Topinard to be 421 c.c. 



The determination of the mass and weight of the brain as 

 expressed in ounces, and of the capacity of the cranial cavity as 

 expressed in cubic centimetres, are only rough methods of com- 

 paring brain with brain, either as between different races of 

 men, or as between men and other mammals. Much finer 

 methods are needed in order to obtain a more exact com- 

 parison. 



The school of Phrenologists represented in the first half of the 

 century by Gall, Spurzheim. and George Combe, whilst recog- 

 nising the importance of the size of the brain as a measure of 

 intellectual activity, also attached value to what was called its 

 quality. At that time the inner mechanism of the brain was 

 almost unknown, for the methods had not been discovered by 

 which its minute structure could be determined. It is true that 

 a difference was acknowledged, between the cortical grey matter 

 situated on the surface of the hemispheres and the subjacent 

 white matter. Spur/.heim had also succeeded in determining 

 the presence of fibres in the white matter of the encephalon, 

 and had, to a slight extent, traced their path. The difference 

 between the smooth surface of the hemispheres of the lower 

 mammals and the convoluted surface of the brain of man and 

 the higher mammals, and the influence which the development 

 of the convolutions exercised in increasing the area of the 

 cortical grey matter, were also known. 



A most important step in advance was made, when, tlirough 

 the investigations of Leuret and Gratiolet, it became clear that 

 the convolutions of the cerebrum, in their mode of arrange- 

 ment, were not uniform in the orclers of mammals which pos- 



1 "Nouvel 

 •-' The stall 



re naturelle," 1895. 

 jf Max I in. 28. 



NO. 1453. VOL. 5DJ 



ses.sed convoluted brains, but that different patterns existed in 

 the orders examined. By his further researches (iratiolet deter- 

 mined that in the Anthropoid apes, notwithstanding their much 

 smaller brains, the same general plan of arrangement existed as 

 in man, though differences occurred in many of the details, and 

 that the key to unlock the complex arrangements in man was to 

 be obtained by the study of the simpler dispo.sition in the apes. 

 These researches have enabled anatomists to localise the convo- 

 lutions and the fissures which separate them from each other, 

 and to apply to them precise descriptive terms. These investi- 

 gations were necessarily preliminary to the histological study 

 of the convolutions, and to experimental inquiry into their 

 functions. 



By the employment of the refined histological methods now 

 in use, it has been shown that the grey matter in the cortex of 

 the hemispheres, and in other parts of the brain, is the seat of 

 enormous numbers of nerve-cells, and that those in the cortex, 

 whilst pos.sessing a characteristic pyramidal shape, present many 

 variations in size. Further, that these nerve-cells give origin to 

 nerve axial fibres, through which areas in the cortex become 

 connected directly or indirectly, either with other areas in the 

 same hemisphere, with parts of the brain and spinal cord 

 situated below the cerebrum, with the muscular system, or with 

 the .skin and other organs of sense. 



Every nerve-cell, with the nerve axial fibre arising from and 

 belonging to it, is now called a Neurone, and both brain and 

 spinal cord are built of tens of thousands of such neurones. It 

 may reasonably be assumed that the larger the brain the more 

 numerous are the neurones which enter into its constitution. 

 The greater the number of the neurones, and the more com- 

 plete the connections which the several areas have with each 

 other through their axial fibres, the more complex becomes 

 the internal mechanism, and the more perfect the structure of 

 the organ. We may reasonably assume that this perfection of 

 structure finds its highest manifestations in the brain of civilised 

 men. 



The specialisation in the relations and connections of the 

 axial fibre processes of the neurones, at their termination in 

 particular localities, obviously points to functional differences 

 in the cortical and other areas, to which these processes extend. 

 It has now been experimentally demonstrated that the cortex 

 of the cerebrum is not, as M. Flourens conceived, of the same 

 physiological value throughout ; but that particular functions 

 are localised in definite areas and convolutions In speaking 

 of localisation of function in the cerebrum, one must not be 

 understood as adopting the theory of Gall, that the mental 

 faculties were definite in their number, that each had its seat 

 in a particular region of the cortex, and that the locus of this 

 region was marked on the surface of the skull and head by a 

 more or less prominent "bump." 



The foundation of a scientific basis for localisation dates from 

 1870, when Fritsch and Hitzig announced that definite move- 

 ments followed the application of electrical stimulation to 

 definite areas of the cortex in dogs. The indication thus given 

 was at once seized upon by David Ferrier, who explored not 

 only the hemispheres of dogs, but those of monkeys and 

 other vertebrates. ^ By his researches and those of many subse- 

 quent inquirers, of whom amongst our own countrymen we may 

 especially name Beevor, Horsley, and Schafer, it has now been 

 established that, when the convolutions bounding, and in close 

 proximity to the fissure of Rolando are stimulated, motor re- 

 actions in the limbs, trunk, head and face follow, which have a 

 definite purposive character, corresponding with the volitional 

 movements of the animal. The Rolandic region is therefore 

 regarded as a part of the motor apparatus ; it is called the motor 

 area, and the function of exciting voluntary movements is local- 

 ised in its cortical grey matter. 



By the researches of the same and other inquirers it has been 

 determined that certain other convolutions are related to the 

 different forms of sensibility, and are sensory or perceptive 

 centres, localised for sight, hearing, taste, smell, and touch. 



Most important observations on the paths of conduction of 

 sensory impressions in the cortex of the convolutions were 

 announced last year by Dr. Flechsig.'^ of Leipzig, so well known 

 by his researches on the development of the tracts of nerve- 

 fibres in the columns of the spinal cord, published several years 

 ago. He discovered that the nerve-fibres in the cord did not 

 become myelinated, i.e. attain their perfect structure, at a 



1 " West Riding Asylum Reports," 1873. 



2 " Die localisation der Cleistigen VorgSnge," Leipzig, 1896. 



