SECTION OF COVERED-EYED MEDUSA 71 



Lastly, the third mode of section is represented 

 in the next cut. Here seven of the marginal ganglia 

 having been removed as before, the eighth one was 

 made the point of origin of a circumferential section, 

 which was then carried round and round the bell in 

 the form of a continuous spiral — the result, of course, 

 being this long ribbon-shaped strip of tissue with 

 the ganglion at one end and the remainder of 

 the swimming-bell at the other. Well, as before, 

 the contraction-waves always originated at the 

 ganglion ; but now they had to course all the way 

 along the strip until they arrived at its other ex- 

 tremity; and, as each wave arrived at that extremity, 

 it delivered its influence into the remainder of the 

 swimming-bell, which thereupon contracted. Now, 

 in this experiment, when the spiral strip is only 

 made about half an inch broad, it may be made 

 more than a yard long before all the bell is used up 

 in making the strip; and as nothing can well be 

 imagined as more destructive of the continuity of 

 a nerve-plexus than this spiral mode of section 

 must be, we cannot but regard it as a very remark- 

 able fact that the nerve-plexus should still continue 

 to discharge its function. Indeed, so remarkable does 

 this fact appear, that to avoid accepting it we may 

 well feel inclined to resort to another hypothesis, 

 namely, that these contraction- waves do not depend 

 for their passage on the nervous network at all, 

 but that they are of the nature of the muscle waves, 

 or of the waves which we see in undifferentiated 

 protoplasm, where all parts of the mass being equally 

 excitable and equally contractile, however severely 



