150 



SCIENCE. 



[N. S. Vol. VII. No. 163. 



investigation of the communities that they 

 form, and of the interlocking of these into 

 greater, more complex communities ; a 

 study of the external configuration of indi- 

 viduals, with reference to their resistance 

 to undue humidity, undue dryness, unusual 

 cold, extreraeheat ; an anatomical studj^ of 

 their several organs as connected with the 

 same factors ; a chemical study of their se- 

 cretions in the same light ; and, finally, a 

 return to that with which I began, a study 

 of their protoplasm in all its phases. 



Anatomy : What is the Morphologic Status of 

 the Olfactory Portion of the Brain ? Pro- 

 fessor Burt G-. Wilder. 

 In view of the multitude of problems now 

 confronting anatomists,* it has seemed to 

 me that the present occasion may be best 

 utilized by discussing, in some detail, a sin- 

 gle topic which has, nevertheless, intimate 

 relations with several others in anatomy 

 and embryology, human and comparative. 

 Most of the points are indicated upon the 

 wall-maps exhibited. f 



Stated more specifically, does the olfactory 



*In 1891 I stated (Records of the Association of 

 American Anatomists, sixth meeting, p. 32) that, in 

 addition to about fifty special questions respecting 

 each of the fifty particular cerebral fissures, there are 

 at least one hundred general problems connected with 

 tliem as a group of features of what is commonly 

 mentioned as a single organ. 



tThese included diagrams of the brains of man, 

 sparrow, turtle, Necturus, Ceratodus, Scymnus (after 

 T. J. Parker), Chimssra, Polyodon, Petromyzon and 

 Bdellostoma : a diagram of the mesal aspect of the 

 human thalamus, etc., exhibiting the location of the 

 aullx ( ' sulcus Monroi ' ) as first described by Reichert, 

 together with the deflection of its cephalic half as pro- 

 posed by His ; and schemas representing (a) the dor- 

 sal aspect of the six definitive segments now recog- 

 nized by me ; viz. : Rhinencephal, Prosencephal, 

 Diencephal, Mesenoephal, Epencephal, Metencephal ; 

 (6) the same as if medisected ; (e) the several brain 

 flexures, especially the diencephalic ; (d) the five dif- 

 ferent topographic relations to the general axis of the 

 brain (as represented by the olfactory crus) of the 

 presumed psychic expansions. 



portion of the brain constitute a definitive segment ; 

 or does it, together ivith the striatum and pal- 

 lium, constitute merely the ' dorsal zone ' of a 

 segment whose ventral zone is the 'pars optica 

 hypothalami,' i. e., the region about the chiasma ? 

 As a basis for the consideration of this 

 question are offered the following proposi- 

 tions, the validity of which each must de- 

 termine for himself : 



1. We must distinguish between the po- 

 tential neuromeres, the precise number of 

 which may not be determined for decades, 

 and the definitive segments, which are con- 

 venient and natural divisions, even if not 

 all of equal morphologic value. 



2. For the determination of the segmental 

 constitution of the brain more reliance is to 

 be placed upon comparative anatomy and 

 embryology than upon the structure and 

 development of that morphologic mon- 

 strosity, the human brain. 



3. The recent enactments of the Anato- 

 mische Gesellschaft upon this subject- (B. 

 N. A., 1895) are based almost exclusively 

 upon the conditions in a single member of 

 the vertebrate community, man ; at the 

 best, even if they apply more or less closely 

 to the other mammals, they constitute an 

 example of ' class-legislation.' 



4. When a writer employs a term in a 

 sense other than either (a) that which is 

 generally accepted, or (b) that in which 

 it was first introduced, or (c) that in which 

 it is used by other writers whose views he 

 may be discussing, it is incumbent upon 

 him to state explicitly the sense in which 

 he proposes to use it. 



The present obstacles to the recognition 

 of a rhinencephalic segment are three, viz.: 

 (1) The common impression as to the in- 

 significance of the olfactory region. (2) 

 The existence, in the higher vertebrates, 

 of the modification designated by me as 

 the diencephalic fiexure. (3) The adverse 

 view adopted in the B. IST. A., based largely 

 upon the assumption that the region 



