432 



NA TV RE 



[September 2, 1897 



is that between the metacarpal bone and the corresponding 

 carpal bone, and not that between the metacarpal bone and the 

 phalanx. In addition, one, or it may be two faint grooves run 

 from within outwards near the middle of the sole. In the infant's 

 foot a groove also extends longitudinally in the centre of the 

 foot. The grooves on the integument of the sole are in harmony 

 with the inner anatomy of the foot, and confirm the statement, 

 already made, that the great toe in man cannot be opposed to 

 the sole, as the thumb can to the palm, for the great curved 

 groove expressing the movement of opposition is wanting. 



In the apes, the condition of the tegumentary grooves in the 

 sole is very different from the human foot. In the Anthropoid 

 group, the ball of the great toe, with its muscles, is marked off 

 by a deep curved groove, which extends from the margin of the 

 cleft between it and the second toe, backwards along the middle 

 of the sole almost as far as the heel. Its depth and extent are 

 associated with the powerful opponent, or grasping action of the 

 hallux. Two other grooves, in front of that just described, 

 pass obliquely across the sole from the cleft between the 

 hallux and the second toe, and reach the outer border of the 

 foot. They are associated with the movements of the four 

 smaller toes, and their obliquity shows that, when the foot is 

 used as a prehensile organ, the object is grasped not only by 

 the great toe being moved towards the sole, but by the smaller 

 toes being moved towards the hallux. From these arrange- 

 ments it is obvious that the pes of the ape is, physiologically 

 speaking, a foot-hand, it is pedimanous. Though anatomically 

 a foot, it can be used not only for support and progression, but 

 for prehension, and, for the latter-named office, the hallux is a 

 more potent digit in the foot than is the pollex in the hand. 

 The external rotation of the thigh at the hip joint, and the 

 power of rotating the leg inwards on the thigh at the knee 

 joint, contribute to make the foot of the ape a more important 

 prehensile instrument, and enable the animal to use it more 

 efficiently for this purpose when sitting, than would have been 

 the case if there had been no contributory movements at the hip 

 and knee. , 



The power of assuming the erect attitude, the specialisation 

 of the upper limbs into instruments of prehension, and of the 

 lower limbs into columns of support and progression, are not in 

 themselves sufficient to give that distinction to the human body 

 which we know that it possesses. They must have coordinated 

 with them the controlling and directing mechanism placed in 

 the head, known as the brain and organs of sense. 



The head, situated at the summit of the spine, holds a com- 

 manding position. Owing to the joints for articulation with 

 the atlas vertebra being placed on the under surface of the skull, 

 and not at the back of the head, and to the great reduction in 

 the size of the jaws, as compared with apes and quadrupeds 

 generally, the head is balanced on the top of the spine. The 

 ligaments supporting it and connected with it are comparatively 

 feeble, and do not require for their attachment strong bony 

 ridges on the skull, or massive projecting processes in the spine, 

 such as one finds in apes and many other mammals. The head 

 with the atlas vertebra can be rotated about the axis vertebra by 

 appropriate muscles. The face looks to the front, the axis of 

 vision is horizontal, and the eyes sweep the horizon with 

 comparatively slight muscular effiart. 



The cranial cavity, with its contained brain, is of absolutely 

 greater volume in man than in any other vertebrate, except in 

 the elephant and in the large whales, in which the huge mass 

 of the body demands the great sensory-motor centres in the 

 brain to be of large size. Relatively also to the mass and 

 weight of the body, the brain in man may be said to be in 

 general heavier than the brains of the lower vertebrates, though 

 it has been staled that some small birds and mammals are 

 exceptions to this rule. 



We have abundant evidence of the weight of the brain in 

 Europeans, in whom several thousand brains have been tested. 

 In the men, the average brain-weight is from 49 to 50 oz. 

 (1390 to 1418 grm.). In the women, from 44 to 45 oz. (1248 

 to 1283 grm. ). The difference in weight is doubtless in part 

 correlated with differences in the mass, weight, and stature of 

 the body in the two sexes, although it seems questionable if the 

 entire difference is capable of this explanation. It is interesting 

 to note that even in new-born children the boys have bigger 

 heads and heavier brains than the girls. Dr. Boyd gives the 

 average for the girl infants as 10 oz. , and for boys 1 1 '67 oz. A 

 distinction in the brain weight of the two sexes is obviously 

 established, therefore, before the child is born, and is not to 



NO 1453, VOL. 56] 



be accounted for by the training and educational advantages 

 enjoyed by the male sex being superior to those of the female 

 sex. 



The brains of a number of men of ability and intellectual 

 distinction have been weighed, and ascertained to be from 55 

 to 60 oz. In a few exceptional cases, as in the brains of Cuvier 

 and Dr. Abercrombie, the weight has been more than 60 oz. ; 

 but it should also be stated that brains weighing 60 oz. and 

 upwards have occasionally been obtained from persons who had 

 shown no sign of intellectual eminence. 



On the other hand, it has been pointed out by M. Broca and 

 Dr. Thurnam, that if the brain falls below a certain weight it 

 cannot properly discharge its functions. They place this 

 minimum weight for civilised people at 37 oz. for the men, and 

 32 oz. for the women. These weights are, I think, too high 

 for savage men, more especially in the dwarf races. We may, 

 however, safely assume that if the brain -weight in adults does 

 not reach 30 oz. (851 grm.), it is associated with idiocy or 

 imbecility. There would seem, therefore, to be a minimum 

 brain-weight, which is necessary in order that the mental 

 functions may be actively discharged. 



We have unfortunately not much evidence of the weight of 

 the brain in the uncultivated and savage races. The weighings 

 made by Tiedemann, Barkow, Reid, and Peacock give the 

 mean of the brain in the negro as between 44 and 45 oz. , a 

 weight which corresponds with that of European women ; 

 whilst in the negress the mean weight is less than in the female 

 sex in Europeans. In two Bush girls fronj South Africa — 

 representatives of a dwarf race — the brain is said to have been 

 34 and 38 oz. respectively. ^ 



From the weighings which have been published of the brains 

 of the Orang and Chimpanzee, it would seem that the brain- 

 weight in these apes ranges from 11 to 15 oz. (312 to 426 grm. ), 

 and the brain-weight appears to be much about the same in the 

 Gorilla. These figures are greatly below those of the human 

 brain, even in so degraded a people as the dwarf Bush race of 

 South Africa. They closely approximate to the weight of 

 newly-born male infants, in whom, as has just been stated, the 

 average weight was 11 '67 oz. For the purposes of ape-life, the 

 low brain-weight is sufficient to enable the animal to perform 

 every function of which it is capable. Its muscular and nervous 

 systems are so accurately coordinated that it can move freely 

 from tree to tree, and swing itself to and fro ; it can seize and 

 retain objects with great precision, and can search for and pro- 

 cure its food. In all these respects it presents a striking con- 

 trast to the infant, having an almost similar brain-weight, 

 which lies helpless on its mother's knee. 



Another line of evidence, of which we may avail ourselves, 

 in order to test the relative size of the brain in the different 

 races of men and in the large apes is to be obtained by deter- 

 mining the internal capacity of the cranium. Examples of the 

 brains of different races (except Europeans) are few in number 

 in our collections, but the crania are often well represented, the 

 volume of the cavity in which the brain is lodged can be 

 obtained from them, and an approximate conception of the 

 size and weight of the brain can be estimated. In pursuing 

 this line of inquiry, account has of course to be taken of the 

 space occupied by the membranes investing the brain, by the 

 blood vessels and the cerebro- spinal fluid. A small deduction 

 from the total capacity will have to be made on their behalf. 



There is a general consensus of opinion amongst craniologists 

 that the mean internal capacity of the cranium in adult male 

 Europeans is about 1500 c.c. {91 '5 cub. in.). The mean 

 capacity of the cranium of fifty Scotsmen that I have measured 

 by a method, which I described some years ago,^ was 1493 c.c. 

 (91 "I cub. in.). The most capacious of these skulls was i77c> 

 c.c, and the one with the smallest capacity was 1240 c.c. 

 Thus, in a highly civilised and admittedly intellectual people, 

 the range in the volume of the brain-space amongst the men 

 was as much as 530 c. c. in the specimens under examination, 

 none of which was known or believed to be the skull of an 

 idiot or imbecile, whilst some were known to be the crania of 

 persons of education and position. In twenty-three Scotswomen 

 the mean capacity was 1325 c.c, and the range of variation was 

 from a maximum 1625 to a minimum iioo c.c — viz., 525 c.c. 



Again I have taken the capacity, by the same method, of a 

 number of crania of the Australian aborigines, a race incapable 



1 Sir R. Quain in Pathological Transactions, 1850, p. 182, and Messrs. 

 Flower and Murie in Journal of Anatomy and Phys., vol. i. p. 206. 



2 Human Crania, Challenger Reports, Pt. xxix., 1884, p. 9. 



