THE FOEM-BELATIONS OF THE HUMAN BEAIN. 305 



adult brain. The central convolutions in front and behind the central 

 fissure; the three frontal gyri, still incompletely separated from one an- 

 other; the superior and inferior parts of the parietal lobe, between which 

 the three components of the fissura interparietalis are visible; finally the 

 temporal lobe divided into three parts — these are all prominent, and, when 

 once understood, make their recognition later in the adult brain a very 

 easy matter. 



The great interest which is shown in the development and perfection of the 

 brain-iisaures is not occasioned purely by morphology. Since the scientific study of 

 the brain has become general, there has been an endeavor to answer the question, 

 whether the intellectual status of the individual may somehow be reflected in the 

 expansion of the surface of the cerebrum. Gall even believed himself justified in 

 laying down the proposition that men ranking especially high intellectually have 

 larger and more richly convoluted cerebrums than others, and that the frontal lobes 

 are preponderantly better developed. 



Here, however, we are dealing with a general impression rather than with the 

 result of exact measurement and comparative observation. Really serious studies in 

 this direction first date from the time when Rudolph Wagner, in 1860, presented to 

 the Gottingen Society of Sciences the report of the investigations which he had made 

 on the brain of the celebrated mathematician. Gauss, and on several other brains of 

 philosophers and men of letters. Since then we have come into possession of a very 

 large number of descriptions of convolutions. 



There is hardly a fissure, hardly a convolution, that cannot now present a small 

 literature of its own. The typical relations as regards the direction and a certain 

 number of possible variations are well known for all the sulci and gyri. We possess 

 descriptions of the surface of the brain, not only of Europeans, but also of repre- 

 sentatives of many foreign peoples. The anthropoid apes have been made the sub- 

 ject of very numerous investigations, and a, very zealous study has been devoted to 

 the other apes by many investigators. The development of the convolutions is now 

 exactly known for man, and many apes also. It has become apparent from these 

 studies (Cunningham) that the embryonic fissures and convolutions appear by no 

 means simultaneously in all individuals, nor have the same configuration when they 

 are once distinctly present. This fact is, therefore, very important, because it con- 

 tains the proof that the cortex of the brain, the organ of the higher intellectual 

 activity, is variously expanded in different individuals, even in the fundament. 



If no mention at all were made of all these numerous investigations while de- 

 scribing the convolutions of the adult human brain, investigations that have made 

 us familiar with the variations to which the individual gyri are subject, it was 

 because these things are, for the present, only to be recorded and as yet are to 

 be brought into no sort of connection with the perfection of the separate intellectual 

 faculties. For investigations of the brain are still wanting entirely which consider, 

 simultaneously with the development of the gyri, the entire intellectual status of a 

 single individual. Even now, when numerous careful researches have finally fur- 

 nished us somewhat of a survey, we are still hardly able to consider such relations. 

 However, the attempt must be made even now to investigate the corresponding cor- 

 tical development for the faculties known to be localized. It is hoped the time will 

 then come when the convolutions will be no longer described simply as such, but 

 only in connection with the questions which their development always gives rise to in 



