MORPHOLOGICAL STUDIES. 
215 
ment which Dr. Eisig puts to me, and in the second place there 
is the answer which Dr. Eisig from his standpoint gives to these 
questions. With the latter I am here little concerned, for the 
answer is purely hypothetical, as Dr. Eisig admits, and no one 
can object to his right to establish as an admitted hypo- 
thesis the view that the lateral sense organs were once con- 
nected with spinal nerves. According to my ideas the evidence 
is entirely wanting, and the quotations from three or four 
authors 1 which Dr. Eisig makes to show that even now spinal 
nerves send branches to the sense organs situate in the trunk, 
do not seem to me to affect the question ; for, as I shall else- 
where show, they are all either vague or of a very doubtful 
character, and as yet no one has figured these connections. 
These remarks also answer his questions as to whence I know 
that such connection was never the case. We know nothing 
of such connection of spinal nerves with the sense organs of the 
lateral line, either now or in the past, and any opinion one may 
express in favour of such a view is only an assumption. 
To the second question, whether the spinal ganglia are not 
homologous with the sense-organ ganglia of the head, I think 
the answer must be decidedly in the negative. 
I regret to be compelled to this result, but I see no way out 
of the conclusion that the spinal ganglia of the trunk are 
homologous with those portions of the cranial ganglia which 
take their origin in the similar position to the spinal, viz. just 
outside the lips of the neural plate. I have never as yet seen 
a trace of the sensory epithelium and ganglia of the sense organs 
in the trunk region of a Vertebrate embryo. Here, of course, 
I except the sense organs derived from the vagus which wander 
into the trunk, as I have shown elsewhere (No. 6, p. 19), by 
displacing the indifferent epiblast. 
I have, moreover, never seen a trace of a sensory epithelium 
1 The authors quoted are Julin (No. 39), Ransome and Thompson (No. 53), 
and Ryder (No. 55). While this paper was passing through the press, the 
supposed connection between spinal nerves and lateral nerve has been totally 
refuted by Professor Dohrn (“ Studien, &c.,” No. xiii, ‘ Mittheil. a. d. Zool. 
Station zu Ncapel,’ Bd. viii, Hft. ii). 
