SECTION OF COVERED-EYED MEDUSA. 85 
on the contraction-waves beyond the areas of 
previous blocking. In such instances, of course, we 
should expect to find what I always observed to be 
the case, viz. that the first contraction-wave which 
passes the barrier is only very feeble, the next 
stronger, the next still stronger, and so on, accord- 
ing as the new passage becomes more and more per- 
meable by use, until at last the contraction-waves 
pour over the original barrier without any per- 
ceptible diminution of their force. In some cases, 
by exploring with graduated stimuli and needle- 
point terminals, I was able to ascertain the precise 
line through which this eruption of stimulating 
influence had taken place.” 
I have now to state the effect upon this hypo- 
thesis which in my opinion has been produced by 
the histological proof that the plexus in question is 
composed of fully differentiated nerves. Briefly, 
then, I think that the hypothesis still holds to the 
extent of being the only one available whereby to 
explain the facts ; but there is this great difference, 
viz. that the hypothesis need not now be applied 
to the genesis of nerve-tissue out of comparatively 
undifferentiated contractile tissue, but rather to the 
increasing of the functional activity of already well- 
differentiated nerve-tissue. In other words, we 
have not now to suppose that nerve-tissue is 
formed de novo in the region of blocking ; but, in my 
opinion, we still have to suppose that the nerve- 
fibres which were already there have their func- 
tional capabilities so far improved by the greater 
demand imposed upon them, that whereas at first 
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