388 Julia B. Platt 
KLAATscH (94) and denied by Röse (94), but through the migration 
into this region of cells similar to those that form the basis of the 
branchial cartilages. Except for the cells that underlie the epithe- 
lium of the mouth, the mesectodermic part of the connective tissue 
is almost entirely consumed in the production of the branchial 
eartilages and the trabeculae. Those cells that remain become for 
me indistinguishable from wandering mesodermie cells, by which I 
would not imply that I believe them to form an identical tissue 
with the mesoderm. I know nothing further about them. 
My conclusions concerning the fate of these wandering cells 
from the neural crest and external ectoderm in Necturus are 
compared below with the results obtained by GORONOWITSCH from 
the study of the neural crest cells in the bird. 
According to GORONOWITSCH, the tissues which may be attributed 
to wandering ectodermic cells, chiefly from the neural crest, are: 
a) neither nerves nor ganglia, but 
b) mesenchymal tissue identical with that derived from the 
mesoderm, 
e) skeletogenous tissue from which the skull in the region of 
the mid-brain is formed, 
d) embryonic nerve-supporting tissue, 
e) the sheath of ScHWANN, 
f) possibly the cutis (from ext. ectoderm cells), 
g) possibly part of the musculature, at least, of the visceral 
arches. 
The tissues derived from the mesectoderm in Necturus are: 
a) both nerves and ganglia, 
b) a connective tissue distinguished by yolk differentiation from 
the mesenchyma, 
ce) skeletogenous tissue from which the branchial cartilages and 
anterior trabeculae are formed, but which takes no part in 
the formation of the skull in the region of the mid-brain, 
d) not embryonic nerve-supporting tissue, but embryonic nerves, 
(ge) 
9 
f) dentine, but not the cutis, 
-g) no musculature in the visceral arches or else-where. 
An evident explanation of part, at least, of the differences in the 
above conclusions based on the study of the bird and of Necturus, 
is given by GORONOWITSCH when he says, that he absolutely loses 
the wandering ectodermic cells in the mesenchyma, and consequently 
