302 
There is one section of ViaNnAL’s work which I desire to notice. 
As the point is of extreme importance and does not appear to have 
been considered by Donrn in this aspect, I feel that no apology is 
needed for bringing it prominently forwards. 
In addition to his interpretation of the nuclei of RANvIER’s nodes 
as mesoblastic, — and this I consider to be erroneous — VIGNAL 
has made important observations on the functions of these bodies. 
He has shown that they are concerned in the lengthening of the 
nerve '), and that to this end they give origin to intercalary segments. 
It appears to me that ViGNAL’s discoveries on this point alone 
should be sufficient to discredit the prevailing view of nerve formation, 
i. e. what Donen aptly terms the process theory. Certainly it would 
be a remarkable and inexplicable circumstance, if the original nerve 
fibre were laid down as an epiblastic process, and if it then underwent 
increase in size or grew at the expense of mesoderm cells. The 
upholders of the process theory?) never felt concerned with the 
increase in size or growth of nerve-fibres when once formed: the dif- 
ficulty had never been stated, and therefore there had hitherto been 
no reason for dealing with it. The obstacle is however there, and 
Chapter II of Vianaw’s work, treating, as it does, of the mode of 
growth of Mammalian nerve will need to be reckoned with by Pro- 
fessor His and those who follow him. 
To the view of nerve histogenesis enunciated by the present 
writer VIGNAL’s observations on this matter form, on the contrary, 
a welcome corollary, and the figures in the text of this chapter are 
very suggestive in relation to the theory of the formation of nerve by 
secretion, i. e. as the result of nuclear activity, which I am led to 
adopt. . 
1) Probably also in its nutrition. 
2) Taking the distance from the lumbar region of man to the muscles 
of the great toe for the sake of argument as represented by one metre, 
in this stretch some 20,000 ganglion cells could be applied end to end 
to form one conducting cord of cells. 
On the same basis were a motor ganglion cell of the anterior horn 
magnified to a diameter of one metre, its axis-cylinder process, reaching, 
according to the current view, to the great toe, would have an apparent 
length of twenty kilometres — a somewhat surprising result! 
Frommannsche Buchdruckerei (Hormann Pohle) in Jena. 
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