6 C. W. M. Poynter 



and hands can be correlated with a remarkable expansion of the 

 cortex in the praecentral region, as shown by the development of 

 a broad gyrus extending from the middle of the praecentral region 

 to form the second frontal convolution." In Dr. Mott's work we 

 may call attention to the fact that the increase in the cortical 

 region is directly related, apparently, to the cortex presiding over 

 the arm and hand centers, and that no correlated change has 

 been shown for any higher or association area. 



The general statement that no work on man has given a sug- 

 gestion of a relation of more or less restricted areas of cortical 

 development to function would create a wrong impression and be 

 incorrect, but we may assert that as yet there are available no 

 positive data. 



The study of convolution variations has been carried out along 

 a great many different lines ; some investigators have sought to 

 tabulate the differences and reduce them to percentages. That 

 this method is frequently used without careful discrimination is 

 obvious from the undoubted fact that all variations are not of 

 the same morphological value. An extreme example of this 

 method of investigation is the work of Kohlbrtigge (1909), who 

 discovered no less than fifteen hundred variations and tabulated 

 eight hundred. 



Klaatsch (1912) suggests an entirely different method of study, 

 at least for ethnological classifications, " nicht die kleinen indi- 

 viduellen Verschiedenheiten der einzelen Furchen sind es, auf die es 

 ankommt, sondern die Kombinationen von Windungs- und Furch- 

 ungs-systemen an den hauptpartien, nicht minder aber audi auf 

 die Gesamtform der grossen Abschnitte und des ganzen Gross- 

 hirns." From this viewpoint one does not see the open fissures 

 of the brain but, as Spitzka suggests, a physiognomy. Since the 

 days of Camper the classification of the human race has been 

 based on anatomical peculiarities, with cranial morphology as the 

 first consideration. From time to time other parts of the skeleton 

 have been added, then the soft parts and finally the brain. 

 Klaatsch suggests a new race classification based on his interpre- 

 tation of brain differences, but as yet it is impossible to say 

 whether it will represent a great departure from the work of 



350 



