248 MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 



has been involved in obscurity. '"Formerly," as an eminent anatomist remarks, 

 " they were considered as a bundle without a system and the artist drew them as 

 he would draw any dishful of macaroni." This state of things undoubtedly arose 

 from studying the human brain alone, and here the excessive complication in the 

 development of secondary and tertiary furrows, produces, apparently, a perfect 

 chaos of convolutions and obscures all idea of regularity of plan. Human brains, 

 moreover, vary greatly in respect to their minor marking, so that we have not as yet 

 what might be termed an average standard adult brain. Whilst some authorities 

 still deny that the fissures and convolutions of the human brain can be elucidated 

 by a study of related animals, I think that all unbiased minds who are familiar 

 with the modern teachings of comparative anatomy and zoology will admit that it 

 is only by such studies, combined with the study of the embryology of the human 

 brain, that any scientific conclusions can be reached, and that the treatise of Gratiolet, 

 " On the Convolutions of Man and the Primates" first laid the foundations for a 

 proper study of the cerebral surface. Meynert also takes as his starting point the 

 brain of a monkey, whilst Bischoff holds that the monkey brain is not a minia- 

 ture model of the human brain, but represents arrested stages in the development 

 of the latter. These opinions are shared by Huschke, Pansch, Huxley, Rolleston 

 and, indeed, by almost all modern observers. 



The morphology of the convolutions as described in the present paper is 

 founded upon an extensive study of the brains of Primates and other animals, 

 as well as those of Man. both in the adult and embryonic stages. The material 

 has been derived almost entirely from my own collections and preparations. 



It is evident that a comparative study of the convolutions in the lower 

 animals and their correspondence with those found in Man is destined to become 

 of considerable importance, and if it can be shown that these convolutions are 

 based upon a symmetrical plan related to the structure of the hemisphere, it may 

 have interesting bearings as regards the functions of the different portions of the 

 cerebral cortex itself. Whether the convolutions bear precise and definite rela- 

 tions to these functional districts, as some suppose, or whether these districts 

 are merely centralized at different points, with boundaries that have no connection 

 with the individual convolutions are questions that remain to be determined. 

 We know that one convolution passes into the next, and that all are in this way 

 connected together in one continuous system. Hence if the separate convolutions 

 do represent distinct centres of definite functional action, then must they also rep- 

 resent definite structural tracts, and be considered as but visible manifestations of 

 deeper relations of structure. 



In this respect the position held by Ecker and some others does not seem to be 

 consistent. Ecker appears to hold the view that the faculties are resident in defi- 

 nite portions of the convolutions; thus he remarks, 1 "the great problem of an organ- 

 ology of the cerebral surface, that is, of an anatomico-physiological knowledge of the 



'Preface to Cerebral Convolutions of Man, Edes' transl. 



