158 JoURNAL oF CoMPARATIVE NEUROLOGY. 
by His (’89, ’90). His work has recently been confirmed by 
the excellent research of Harrison (:01). The latter was 
able to show that in two cases dorsal processes from bipolar 
neuroblasts of the sensory ganglion broke through the bound- 
ing membrane of the nerve chord, while ventral processes from 
the same cells were traced to the periphery. Both His and 
Harrison have proved that the axis-cylinders and dendrites of 
motor elements originate as processes from a single cell; they 
traced the axis-cylinder processes to the very point where the 
nerve fibers appear; but in no case did either investigator de- 
monstrate direct connection between these processes and the 
embryonic nerve fibers. Harrison states moreover that: ‘‘Die 
ersten motorischen Fasern sind schon vorhanden, ehe wuber- 
haupt lose Zellen in der Gegend der Austrittsstelle zu finden 
sind.” 
Directly contrary to the observations of His and Harri- 
SON, and in agreement with those of BALFour (’76) and DoHRN 
(91) are the preliminary statements of BeTHE (: 02) as to the 
histogenesis of the nerve elements in the chick: (1) Before the 
axis-cylinder processes of the neuroblasts break through the 
bounding membrane of the chord, the fundaments of nerve 
fibers are formed as chains of cells; (2) coincident with the 
breaking through of the processes, many primitive fibers may 
be observed in the myotomes; (3) processes of the bipolar 
cells which form these nerve fibers in the myotomes may be 
traced into the chord with the same distinctness with which the 
processes of the neuroblasts (of His) may be traced out of it, 
and often the union of processes from neuroblast and primary 
nerve cell may be observed; (4) the primitive nerve fibers are 
differentiated simultaneously from an entensive chain of cells 
extending from the central organ to the periphery; (5) these 
cells increase in number only by karyokinesis ; not until the 7th 
to goth day of development are the neuro-fibrillae formed. 
BETHE concludes from these observations that each nerve ele- 
ment represents a group or society of cells, rather than a single 
cell individual. His statements are as yet unsupported by pub- 
lished figures, but they agree both with the observations of 
