180 
J. BEARD. 
direct observation, but I do not hesitate for a moment in ex- 
pressing the opinion that such is the case. If this be true it 
follows that a typical posterior root of a cranial nerve, that is, 
a root passing to a gill-cleft, is composed of elements derived 
from at least three sources : there is, firstly, the portion which 
corresponds to the true spinal ganglion 1 in its derivation from 
the epiblast just outside the neural plate (neural ganglion) ; 
secondly, a portion formed in connection with the branchial 
sense organs (lateral ganglion) ; and thirdly, a portion derived 
from the continuation of the lateral column in the head. 
In addition, a part must he added comparable to the sym- 
pathetic ganglia of the trunk, and this portion is probably, as 
occurs in the case of spinal ganglia, contained in the portion 
of the ganglion derived from the epiblast, just outside the 
neural plate. 
Here we are faced by some interesting problems, which I 
will afterwards discuss. 
His (No. 34, p. 394) and others have raised objections to 
the view of Balfour, that the cells derived from the neural 
ridge or crust are the Anlage of the posterior roots of the 
cranial nerves. Balfour’s phraseology has been used by Mar- 
shall, Spencer, van Wijhe, myself, and others. No doubt 
objections may be urged against the use of this phraseology as 
accurately representing all the facts. 
While I admit that these cells are more a ganglionic Anlage 
than that of a nerve, there are two points which must be urged 
in extenuation of the offence, if offence it be. In the first 
place, Balfour, Marshall, van Wijhe, and all of us who have 
used this phraseology, have done so, in the sense of the inclu- 
sion in the term posterior root, both root and ganglion of the 
nerve; and secondly, in the head at any rate, in addition to 
the cell processes which grow from the ganglion into the cen- 
tral organ, it can be demonstrated (fig. 103) that some of the 
cells of the ganglionic Anlage pass over iuto the root of the 
nerve, and take a direct share in its formation. This question 
1 This portion of the cranial ganglion is possibly only morphologically 
an equivalent to the sympathetic part of a spinal ganglion. 
