OCTOBEK :iO, 1003.] 



SCIENCE. 



549 



when the brain doos not fully occupy the 

 cranial cavity. 



At an early period in the phylofreny of 

 the vertebrate skull the structure of the 

 greater part of the cranial wall changes 

 from membranous tissue into cartilage, the 

 portion persisting as membrane being situ- 

 ated near the median dorsal line. lu the 

 higher vertebrates the rapid and early ex- 

 pansion of the dorsal part of the fore-brain 

 is so marked that the cartilaginous growth 

 fails to keep pace with it, and more and 

 more of the dorsal wall of the cranium re- 

 mains membranous, and subsecjuently ossi- 

 fies to form membrane bones. Cartilage, 

 though constituting a firmer support to the 

 brain than membrane, does not possess the 

 same capacity of rapid growth and ex- 

 pansion. The head of a young child is 

 relatively large, and its skull is distin- 

 guished from that of an adult by the small 

 size of the cartilaginous base of the cranium 

 as compared with the membranous vault. 

 The appearance of top-heaviness in the 

 young skull is gradually obliterated as age 

 advances, by the cartilage continuing slowly 

 to grow after the vault has practically 

 ceased to enlarge. These changes in the 

 shape of the cranium are associated with 

 corresponding alterations in that of the 

 brain, and it appears to me that we have 

 here an illustration of how the conditions 

 of skull growth may modify the general 

 form of the brain. 



"Whatever may be the precise influences 

 that determine skull and brain growth, 

 there can be no doubt but that within cer- 

 tain limits the external form of the cra- 

 nium serves as a trustworthy guide to the 

 shape of the brain. Statements such as 

 those by Dr. J. Deniker ('The Races of 

 ilan,' p. 53), 'that the inequalities of the 

 external table of the cranial walls have no 

 relation whatever to the irregularities of 

 the inner table, and still less have anything 



in common with the configuration of the 

 various parts of the brain,' are of too gen- 

 eral and sweeping a character. Indeed, 

 various oliservers have drawn attention to 

 the fact that in certain regions the outer 

 surface of the skull possesses elevations and 

 depressions which closely correspond to de- 

 finite fissures and convolutions of the brain. 

 Many years ago Sir William Turner, who 

 was a pioneer in eranio-cerebral topog- 

 raphy, found that the prominence on the 

 outer surface of the parietal bone, known 

 to anatomists as the parietal eminence, was 

 situated directly superficial to a convolu- 

 tion of the parietal lobe of the brain, which 

 he consequently very appropriately named 

 'the convolution of the parietal eminence' 

 Quite recently Professor G. Schwalbe has 

 shown that the position of the third or 

 inferior frontal convolution is indicated 

 by a prominence on the surface of the cra- 

 nium in the anterior part of the temple. 

 This area of the brain is of special interest 

 to all students of cerebral anatomy and 

 physiology, since it was the discovery by 

 the illustrious French anthropologist and 

 physician, ]\I. Broca, that the left inferior 

 frontal convolution was the center for 

 speech, that laid the scientific foundation 

 of oiir present knowledge of localization of 

 function in the cei-ebi-al cortex. This con- 

 volution is well known to be much moi-e 

 highly developed in man than in the an- 

 thropoid apes, and the presence of a human 

 cranial speech-bump is usuall.v easily dem- 

 onstrated. The faculty of speech, however, 

 is such a complicated cerebral function 

 that I would warn the 'new' phrenologist 

 to be cautious in estimating the loquacity 

 of his friends by the degree of prominence 

 of this part of the skull, more particularly 

 as there are other and more trustworthy 

 methods of observation by which he can 

 estimate this capacity. 



In addition to the prominences on the 



