604 



SCIENCE. 



[N. S. Vol. XIV. No. 355. 



The present occasion might appear to be 

 peculiarly appropriate for my taking stock 

 of our anthropological possessions and sum- 

 ming up the numerous additions to our 

 knowledge of ' man and his doings ' which 

 have been made during the century which 

 Las just passed. Such a task, however, is 

 surrounded with so much difficulty that I 

 shrink from undertaking it. The scope of 

 the subject is enormous, and the studies in- 

 volved so diverse and so varied that I feel 

 that it is beyond my power to give any 

 comprehensive survey of its development in 

 all its parts. I prefer therefore to confine 

 my remarks to that province of anthropol- 

 ogy within which my own work has been 

 chiefly carried on, and from this to select a 

 subject which has for some years held a 

 prominent place in my thoughts. I refer 

 to the human brain and the part which it 

 has played in the evolution of man. 



One of the most striking peculiarities of 

 man, when regarded from the structural 

 point of view, is the relatively great size of 

 his brain. Although with one or two ex- 

 ceptions the several parts of the brain are 

 all more or less involved in this special de- 

 velopment, it is the cerebral hemispheres 

 which exhibit the preponderance in the 

 highest degree. This characteristic of the 

 human brain is rendered all the more sig- 

 nificant when we consider that the cerebral 

 hemispheres cannot be looked upon as being 

 primitive parts of the brain. In its earliest 

 condition the brain is composed of three 

 simple primary vesicles, and the cerebral 

 hemispheres appear in a secondary manner 

 in the shape of a pair of lateral oflFshoots or 

 buds which grow out from the foremost of 

 these primitive brain-vesicles. 



The offshoots which form the cerebral 

 hemispheres are found in all vertebrates. 

 Insignificant in size and insignificant in 

 functional value in the more lowly forms, 

 a steady increase in their proportions is 

 manifest as we ascend the scale, until the 



imposing dimensions, the complex struc- 

 ture, and the marvelous functional poten- 

 tialities of the human cerebral hemispheres 

 are attained. In their development the 

 cerebral hemispheres of man rapidly out- 

 strip all the other parts of the brain, until 

 they ultimately usurp to themselves by far 

 the greater part of the cranial cavity. To 

 the predominant growth of the cerebral 

 hemisphere is due the lofty cranial vault of 

 the human skull ; to the different degrees 

 of development and to the different forms 

 which they assume are largely due the va- 

 riations in cranial outline in different indi- 

 viduals and different races — variations in 

 the determination of which the craniol- 

 ogist has labored so assiduously and 

 patiently. 



I think that it must be manifest to every 

 one that the work of the craniologist, if it 

 is to attain its full degree of usefulness, 

 must be founded upon a proper recognition 

 of the relation which exists between the 

 cranium and the brain, or, in other words, 

 between the envelope and its contents. 



The cranium expands according to the 

 demands made upon it by the growing 

 brain. The initiative lies with the brain, 

 and in normal conditions it is questionable 

 if the envelope exercises more than a very 

 subsidiary and limited influence upon 

 the form assumed by the contents. The 

 directions of growth are clearly defined 

 by the sutural lines by which the cranial 

 bones are knit together ; but these are so 

 arranged that they admit of the expansion 

 of the cranial box in length, in breadth 

 and in height, and the freedom of growth 

 in each of these different directions has in 

 all probability been originally determined 

 by the requirements of the several parts of 

 the brain. 



The base or floor of the cranium, sup- 

 porting as it does the brain- stem or the 

 parts which possess the greatest phyloge- 

 netic antiquity, and which have not under- 



