MOEPHOLOGICAL STUDIES. 
195 
die letzten Enden der FiDger und der Zehen ihre Nerven 
erhalten haben.” 
To return to nay own observations. I have as yet only in- 
vestigated Sharks and Lizards on this point. The results, so 
far as they concern the latter group, will be given later along 
with observations on the anterior roots of the cranial nerves. 
Figs. 58, GO, 62, 53, 54, 56 and 61, on PI. XIX, are intended to 
illustrate the development of anterior roots of spinal nerves in 
Elasmobranchii. One of the very earliest stages in the deve- 
lopment of an anterior root (a) is shown in fig. 58 (Pristiurus), 
and it possibly corresponds to the stage figured by Professor 
His in the paper quoted above (No. 34, fig. 1). There is no 
possibility of recognising “ parablastic ” cells in this section, 
and one sees that while the root is partially fibrous there is at 
least one nucleus passing out of the spinal cord, either entirely 
or partly after cell division. A slighter later stage is repre- 
sented in figs. 60 and 61. The fibres of the nerve have reached 
the muscle-plate, 1 but there are also two nuclei visible in the 
nerve-cord lying partly also in the cord. There are here also 
plenty of mesoblast — pardon, “ parablast ” cells in the neigh- 
bourhood. But they are not destined for the nerve, but are about 
to enclose the notochord to form the body of the vertebra. 
Later stages in the development are figured in figs. 54, 56. 
Here, too, the fibrous nature of the nerve is very obvious, but 
one also observes a vast number of nuclei within the nerve, 
which one cannot regard, from their form and characters, as 
otherwise than offsprings of the nuclei which have passed at 
earlier stages, and even still continue to do so (figs. 60,54,61), 
from the anterior cornu to the nerve. When His regards the 
nuclei here present as mesoblastic or “ parablastic ” cells, his 
view is just as much a gratuitous assumption as the whole 
parablastic doctrine, as the Zwischenstrang ganglionic forma- 
tion in the trunk, and as the identification of a certain ganglion 
1 The end plates of muscles (and of the electric organ) are derived from 
ganglionic cells, which wander in this way in these early stages from the 
anterior horn to the muscle-plate. Several figures show this, and 1 shall treat 
of the matter at length elsewhere. 
