250 MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 



arranged around the cerebral peduncles, and that the principal or typical convolu- 

 tions and fissures bear definite and symmetrical relations to these buds. In other 

 words, in the development of the cerebrum, the fissures represent lines of 

 retarded growth with respect to the convolutions, and having thus a morpho- 

 logical significance in reference to the cell growth of the brain, they may also, pos- 

 sibly, represent lines of structural demarcation. On the same subject Pansch re- 

 marks, 1 "in any case the convolutions owe their origin as folds to a difference in 

 the strength of growth of different portions of the cerebral surface." 



With regard, therefore, to the cause of the production of cerebral fissures three 

 different views are held. According to one of these, all the fissures of the cerebral 

 hemispheres are produced by a process of mechanical packing ; that is, the brain, 

 developing more rapidly in size than the cavity of the skull, adapts itself to its 

 constrained position by folding along the lines of least resistance, and these lines of 

 least resistance are represented by the various fissures of the cerebral surface. Ac- 

 cording to the second view, the cerebral fissures represent lines of retarded cere- 

 bral growth, and have, therefore, a structural significance depending upon processes 

 of cell growth within the mass of the brain itself. The last view is merely a com- 

 bination of the other two, and may really be regarded as included under the second. 

 However, we shall discuss this question more thoroughly hereafter. 



There is also a difference of opinion as regards the regularity or irregularity of 

 arrangement of the fissures and gyres : whether they are or are not founded on 

 any definite plan. Recent anatomists have with few exceptions come to the con- 

 clusion that they are founded upon a perfectly uniform and definite atrangement ; 

 and Huschke, BischofF and Pansch, have each given out independent views as 

 regards the plan of this arrangement. With the plans as given by these anato- 

 mists I have not been able to agree; and the principal object of the present paper 

 is to direct attention to a new theory as to the arrangement of the typical fissures, 

 especially in the Primates, and to found thereon a new general system of nomen- 

 clature that shall bind together in one comprehensive whole the various isolated 

 and conflicting views and make clear the difficulties in the synonymy of this in- 

 tricate and perplexing subject. 



Before proceeding with this, however, it will be necessary to review briefly 

 the labors of previous observers in this field, especially prior to the year 1880, in 

 order that the progress of opinion and the present state of the subject may be more 

 clearly comprehended. I must, therefore, ask indulgence for the somewhat 

 extended review of the literature of the subject which I feel compelled to give, for 

 the reason that it would be extremely difficult, if not impossible, to reconcile the 

 various conflicting opinions held at the present time by numerous observers with 

 the new method of classification and arrangement of the fissures and convolutions 

 which I shall offer for consideration and study. This becomes the more necessary 

 because, so far as I am aware, no one has as yet attempted to give a complete and 



1 Ueber die typische Anordnung der Furchen und Windungen, etc.; Arcbiv fur Anthropologic, 1869. 



