SECTION OF COVERED-EYED MEDUS#., 77 
sage of a wave of stimulation, is a sight as beautiful 
as it is unique; and it affords a first-rate oppor- 
tunity of settling this all-important question, namely, 
Will this conductile or nervous function’ prove 
itself as tolerant towards a section of the tissue as 
the contractile or muscular function has already 
proved itself to be? For, if so, we shall gain nothing 
on the side of simplicity by assuming that the 
contraction-waves are merely muscle-waves, so long 
as the conduction or undoubtedly nervous waves 
are equally able to pass round sections interposed 
in their path. Briefly, then, I find that the nervous 
waves of stimulation are quite as able to pass round 
these interposed sections as are the waves of con- 
traction. Thus, for instance, in this specimen (Fig. 
12), the tentacular wave of stimulation continued 
to pass as before, even after I had submitted the 
parallelogram of tissue to the tremendously severe 
form of section which is represented in the illustra- 
tion; and this fact, in my opinion, is one of the most 
- important that has been brought to light in the whole 
range of invertebrate physiology. For what does it 
prove? It proves that the distinguishing function 
of nerve, where it first appears upon the scene of 
life, admits of being performed vicariously to almost 
any extent by all parts of the same tissue-mass. If 
we revert to our old illustration of the muslin as 
representing the nerve-plexus, it is clear that, how- 
ever much we choose to cut the sheet of muslin with 
such radial or spiral sections as are represented in 
the illustrations, one could always trace the threads 
of the muslin with a needle round and round the 
