Anatomical Characters of the Human Brain. 25 



came from a man or woman is much like identifying the sex of the 

 individual from which a given skull came. I am not so optimistic 

 and would rather take my' chances with the skull. 



In the article by Schwalbe and Pfitzer mentioned above many 

 anatomical variations are tabulated and there do not seem to be more 

 variations in the male than in the female, but the percentage of vari- 

 ations is by no means always alike in the two sexes. If there is a 

 percentage difference according to sex in a special variation it tends 

 to remain constant in various sets of statistics and does not become the 

 same as the records are increased in number. Moreover, "bei den 

 weiblichen Fallen werden in der Kegel die Werthe viel rascher 

 constant als bei den mannlichen." In other words, a smaller number 

 of records are required in the female than in the male to obtain the 

 true percentage of variations. How much this indicates is by no 

 means clear, but this conclusion should be that there is not a simpler 

 type, but less variations in the female, which appears to be the opinion 

 of Retzius regarding the female brain. 



We have tested this difference by grouping the illustrations of 

 brains in the great Atlas of Retzius under simple and more complex 

 types, without knowing whether the picture of a brain in question 

 was from a man or from a woman and obtained the result given on 

 page 19. In the first line in the table my estimates are found with 

 the percentages below them. In the second line another estimation by 

 'Dr. Sabin is given, and in the third line one by Dr. Melius. In 

 general the opinion expressed in these estimations does not bear out 

 the notion that the configuration of the brains of women is of a 

 simpler type than in those of men. 



This, however, is only our opinion regarding the complexity of the 

 gyri and sulci of pictures of brains. But Retzius has tabulated in 

 an excellent way a number of concrete data of 100 brains which can 

 easily be tested in other specimens. These include a number of 

 variations, such as the central sulcus communicating with the fissure 

 of Sylvius, regarding which there can be little difference of opinion. 

 There are in all 73 such records, 19 being of the norm and 56 of 

 variations. Each of these records can be entered a second time by 

 subtracting its frequency in percentage from 100. Thus, if the central 



