36 Edward F. M alone. 



illustrations unfortunately show almost nothing ot the various cell groups, 

 but his concise description is most valuable. 



Worthy of special notice is the valuable contribution of Friedemann 

 entitled Die Cytoarchitektonik des Zivisvhenhirns der Cercopitheken mit 

 besonderer Beriicksichtigung des Thalamus opticus. As the title indicates 

 more attention is paid to the thalamus than to the hypothalamus, although 

 both the pars mammillaris and the pars optica are by no means neglected. 

 In this article Friedemann takes into consideration my monograph on the 

 human diencephalon. To consider intelligently Friedemann's account of the 

 cell groups of the hypothalamus it is necessary to realize that his chief 

 purpose is to subdivide this region into topographical cell groups, which 

 are not necessarily composed exclusively ot one type of cell, but may repre- 

 sent complex centers formed by the overlapping of several primary nuclei; 

 on the other hand he has occasionally divided a cell mass, composed of cells 

 of the same type, into subgroups whenever factors other than cell character 

 (such as number and grouping of cells) would permit. In this he has con- 

 sistently endeavored to give us a topographical subdivision into as many 

 areas as may possibly be distinguished in cell preparations. It is accord- 

 ingly evident that my cell groups (primary nuclei i have been set aside in 

 virtue of the possession of one type of cell which corresponds to some known 

 or unknown cell function or functions and that the topographical value of 

 my work is primarily concerned with the location and distribution of 

 such a single cell type; and on the other hand it is evident that Friede- 

 mann's subdivision, not being confined to this one criterion of cell character, 

 results in a much more minute subdivision which is of great value in exact 

 orientation, and that his cell groups may represent primary nuclei, portions 

 of such nuclei, or complex nuclei, according to the criteria employed in the 

 establishment of each cell group. Apparently Friedemann has not grasped 

 this fundamental difference in our aims, since (p. 312) he says: So xvichtig 

 auch u. a. die von Malone festgesteijte Tatsaehc ist, dass im Thalamus 

 opticus keine ZeUen vom viotorischen Typus vorkomm,en, so sehr wir auch 

 in vielen Einzelheiten mit diesem Autor iibereinstimmen, als topographis- 

 ches Einteilungsprinzip konnen wir seine Methode nicht anerkennen. 

 It is certainly my earnest desire that no one should consider the method 

 I have employed as a topographisches Einteilungsprinzip. since I myself 

 have never so considered it, and had supposed that I had made this fact 

 evident. But Friedemann's work is something more than a pure topo- 

 graphical subdivision, since he has informed us as to whether a cell group 

 has been recognized on account of its cell type, or whether it is differen- 

 tiated from the surrounding cells on the basis of other criteria; in other 

 words he has, in giving us this minute and most valuable topographical 

 subdivision, not lost sight of the distribution of the various cell types. The 

 fact that Friedemann and myself have subdivided the diencephalon from 

 different points of view is a fortunate circumstance, and the difference in 

 results is to be expected and welcomed. Other subdivisions from other 

 standpoints are desirable, but it is essential that we be accurately informed 



