MORPHOLOGICAL STUDIES. 
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32 — 36, 21, 13, 17, 43 — 45, where the Anlage of the ganglia 
sits upon and between the dorsal lips of the neural plate and 
prevents the closure and fusion of the latter. 
The next step is the further proliferation and removal of the 
Anlagen to the sides of the spinal cord. In the words of most 
authors, we have now got to Marshall’s neural ridge or crest, 
and the Anlagen “ begin to grow out of the spinal cord” 
(Marshall, Nos. 45, 46). 
I think that in the preceding lines I have shown clearly 
enough that there is really no outgrowth from the spinal cord, 
nor do I find myself in the position to support Marshall’s view 
of the origin of the ganglia from a neural ridge. From the 
time of their first formation the ganglionic Anlagen appear to me 
to be segmented, and if the Anlage of one segment passes over 
into that of another in this and some of the following stages, I can 
see in this no reason for saying that the spinal ganglia arise from 
an uusegmented ridge of cells. No one attaches great morpho- 
logical importance to the origin of the muscle-somites from an 
apparently unsegmented structure, an origin which is condi- 
tioned by the mode of formation of the cell elements, and as 
all traces of such a continuous structure soon disappear, the 
whole of its elements passing over into the various spinal 
ganglia without leaving any permanent “ commissure,” I 
must hold that if we are to say that the spinal ganglia are 
outgrowths of a neural ridge, we must not forget two things : 
that the outgrowths begin as epiblastic buds long before the 
neural ridge stage ; and secondly, that the whole of the neural 
ridge is absorbed by the various spinal ganglia. This latter 
point is all the more necessary seeing that at least one 
observer has suggested as an hypothesis worthy of proof the 
origin of the lateral nerve of fishes from the remains of the 
neural ridge. M. Julin says (No. 39, p. 31), “ Dans mon idee 
le nerf lateral, tel qu’il se trouve constitue cliez 
l’Ammocoetes ne serait que le reste de la Crete 
neurale, ce qui expliquerait ses rapports avec les 
racines du vague et les branches dorsales des nerfs 
spinaux dorsaux.” He is further of opinion that this 
