l6o BIOLOGICAL LECTURES, 



sideration that his own personal convenience and preferences, and 

 even those of all his distinguished contemporaries, should be held of 

 little moment as compared with the advantages which reform may 

 insure to the vastly more numerous anatomical workers of the future. 



Commentaries npon Table III. 



Its purpose is twofold: {a) to indicate, according to my 

 present information and belief, the number and constitution of 

 the definitive encephalic segments; (b) to illustrate the verbal 

 correlations between the names of the segments themselves 

 (column 2), and those of (3) their major cavities, (4) their 

 membranous parietes, and (5) their vascular plexuses. 



It is in some respects an amplification of the table on page 

 409 in W. and G. ('82). It differs from that in my later paper 

 ('89a, 121) in {a) the recognition of the rhinencephal, and {b) 

 the vertical arrangement of the segments. 



From Schwalbe's table ('81, 397) it differs mainly in the 

 absence of any attempt to indicate the relative "values " of the 

 several segments upon embryologic or other grounds. 



In this respect it differs also from that of His ('95, 161). In 

 this latter, moreover, I have not as yet succeeded in recognizing 

 consistency with (a) his other table on page 158; {b) the seg- 

 mental arrangement employed in the German list of neural 

 terms (80-87); (^) ^ discriminating use of terms; {d) due 

 regard for precedent, or (c) the facts of comparative anatomy 

 as I interpret them. 



Conceding the high authority of Professor His as to the 

 embryology of man, I nevertheless believe it to be altogether 

 undesirable to infer the segmental constitution of the verte- 

 brate brain from the conditions presented during the develop- 

 ment of the human organ. Indeed, if the embryology of other 

 forms were also taken into account, the number of potential 

 *' neuromeres " would be unmanageably large, even if any two 

 investigators could agree at present as to how many should be 

 recognized. 



While anticipating that the problems involved will be eventu- 

 ally elucidated upon the basis of all the facts concerned, I 



