Herrick, Histogenesis of the Cerebellum. 67 



bryological literature is full of such usages and no confusion 

 was anticipated therefrom, though it has resulted in the case of 

 some reviewers untrained in embryology. On p. 669 of 

 Schaper's paper we read that " in der Deckplatte der Median- 

 furche und in den I5egrenzungsgebieten der beiden Ressus lat- 

 erales wir drei Orte vor uns haben, von denen nunmehr das 

 neue Material zur weiteren Entwicklung das Kleinhirns bezogen 

 wird." These statements are anticipated in the first number of 

 this Journal and fully illustrated, Schaper then proceeds to dis- 

 cuss the superficial cell layer of the cerebellum which, he says, 

 " findet sich, so veil wir wissen, nur im Kleinhirn." He indeed 

 says " I believe that my observations derived from faultless 

 preparations warrant me in supporting Herrick's theory and to 

 extend it by adding that, in fishes at least, the ' Deckplatte der 

 Medianfurclie ' participates in this process, a fact which seems 

 to acquire special significance from considerations to be men- 

 tioned later." The descriptions and figures given in the article 

 referred to and subsequently will show that this locus was es- 

 pecially recognized by us as a source of proliferation. Thus 

 on p. 13, "While in this case [black snake] the organ 

 does not undergo reflection but remains a leaf-like organ, longi- 

 tudinal sections indicate that proliferation is most rapid near the 

 tip, and a dense clustre of cells is pushed dorsad and cephalad 

 upon the dorsal surface." Respecting the source of the ele- 

 ments the same passage continues "There is every reason to 

 conclude from these sections that the cells of Purkinje likewise 

 spring from near the ventricular border. At the tip and lateral 

 margins, the layer of these in the embryo comes in contact with 

 the epithelium, and the cells which are obviously multiplying 

 rapidly, either spring from the epithelium by subdivision of its 

 undifferentiated cells or the multiplication of special germination 

 cells. The neuroblasts at first become spindle-shaped and give 

 rise to a process which passes cephalad. Nearer the base the 

 layer of Purkinje cells is represented by a thick nucleary zone 

 from the epithelium. At the very base, however, there is a 

 superficial dorsal cell-aggregate which likewise seems to have its 

 origin in the epithelium of the ventricle," On the ninth page 



