182 
J. BEAKD. 
ganglia in the head of the Chick attracts the attention in good 
sections was also a reason for fully investigating the develop- 
ment in this animal; for the question naturally arises, Are these 
appearances primitive, or is the development modified in some 
way or other in the Chick? One could hardly hope to maintain, 
as a strict morphologist would be almost bound to do, if he had 
only Onodi’s researches to go upon, that the mode of develop- 
ment of the cranial ganglia in the Chick is a more primitive 
one than that in Sharks. The facts, which I had discovered 
before seeing Onodi’s paper, were at first a great puzzle to me, 
a puzzle to which Onodi’s researches have given no solution ; 
for, according to him, and so far he agrees with Marshall 
(No. 46), the cranial ganglia of the Chick differ entirely in 
mode of development from the ganglia, cranial and spinal, of all 
the other forms. Sharks, Lizards, Mammals, &c., which he had 
examined. Indeed, he maintains — and I find this attitude a 
surprising one in the man who had seen the true development 
in the cranial ganglia of the Chick — he maintains that in all 
other cases the ganglia, both cranial and spinal, are developed 
as outgrowths of a ganglion ridge (neural ridge of Marshall), 
and this in its turn owes its origin to the central nervous 
system. 
Seeing that my researches on the cranial ganglia of the 
Chick are partly a confirmation of Onodi’s, it might be sup- 
posed that there was no necessity for giving them in detail. 
However, I am of a different opinion, for they do not agree 
with Onodi’s results on all points, and on the fundamental 
question whether the ganglionic Anlagen of the head are or 
are not parts of the central nervous system, Onodi says nothing. 
As he holds that in all other cases the ganglia, spinal and 
cranial, are outgrowths of the central nervous system, his 
position as a comparative embryologist is not a very logical 
one. The first traces of the ganglia, both cranial and spinal, are 
met with in the Chick between the twenty-second and twenty- 
sixth hours of incubation. In such embryos there are on the 
average from two to ten body-somites or protovertebrae, and 
it is in such embryos that evidence of the epiblastic origin 
