q6 wheeler. '[Vol. VIII. 



embryo in which he finds a neuroblast in either lateral cord 

 and three symmetrically arranged cells of the same character 

 in the median cord. Similiar median cells were seen in Ljccilia. 

 He refers to Korotneff's observations on Gryllotalpa and states 

 that he has found the lateral "ganglionare Grosszellen " in Lhia. 

 He is inclined to regard them as a widely occurring differen- 

 tiation of the ectoderm. 



In a subsequent paper ('9o) Graber describes and figures a 

 foliated condition of the ganglia in the nerve-cord of Stcno- 

 botJinis. In Fig. 52 the neuroblasts are distinctly seen, and in 

 one lateral cord five, in the other four pillars of cells may be 

 distinguished. So far as the neuroblasts are concerned, he 

 cannot be said to have added anything to Korotneff's account. 



Nusbaum ('9i), in a recent Polish paper on the development 

 of Mcloc, figures neuroblasts in the lateral cords. They are 

 frequently represented in mitosis — the spindle-axes being in 

 some cases perpendicular to the surface of the ganglia (Figs. 

 94, 95) while in others (Fig. 107) they are parallel to the 

 surface, as in Doryphora. Such portions of the text as were 

 translated for me contained nothing new on these structures, 



Viallanes, in two recent papers ('90^ '90^) on the structure 

 of the nervous system in the embryo Mantis, comes to con- 

 clusions agreeing with my own, which were arrived at inde- 

 pendently. His observations on the neuroblasts may be 

 briefly summarized in his own words ('90^ p. 293) : " A I'ori- 

 gine le bourrelet primitif n'est qu'un simple epaississement 

 de I'exoderme, c'est-a-dire une region de ce feuillet dont 

 les cellules sont devenues columnaires et ont augmente de 

 volume. Bientot ces cellules se multiplient et se divisent en 

 deux couches. Tune superficielle {derniatogbie) , I'autre profonde 

 ganglioghie) . A une periode plus ou moins tardive, suivant la 

 region consideree, la couche des cellules dermatogenes se 

 separe de la couche des cellules gangliog^nes et devient I'hypo- 

 derme. Les cellules gangliogenes en se multipliant donnent 

 naissance aux cellules ganglionnaircs T 



Viallanes' figures do not show a regular arrangement of the 

 cells budded forth from the neuroblasts, and he has not de- 

 scribed the neuroblasts of the median cord, probably because 



