SECTION OF NAKED-EYED MEDUSiE. 121 



it supposes to escape from a severed phalanx of 

 nerve-fibres, and then to reach the manubrium after 

 being diffused through many or all of the other 

 radial lines (such stimuli thus converging from 

 many directions), are responded to when they reach 

 the manubrium, not by any decided localizing action 

 on the part of the latter, but, as the hypothesis 

 would lead us to expect, by the tentative and 

 apparently random motions which are actually 

 observed. Moreover, we must not neglect to notice 

 that these tentative or random movements resemble 

 in every way the localizing movements, save only 

 in their want of precision. Again, this hypothesis 

 is rendered more probable by the occurrence of 

 those gradations in the localizing power of the 

 manubrium which we have seen to be so well 

 marked under certain conditions. The occurrence 

 of such gradations under the conditions I have 

 named is what the theory would lead us to expect, 

 because the closer beneath a section that a stimulus 

 is applied, the greater must be the immediate lateral 

 spread of the stimulus through the plexus before it 

 reaches the manubrium. Similarly, the further the 

 circumferential distance from the nearest end of such 

 a section that the stimulus is applied, the greater will 

 be its lateral spread before reaching the manubrium. 

 Lastly, the present hypothesis would further lead 

 us to anticipate the fact that when Tiaropsis in- 

 dicans is prepared as represented in Fig. 23, the 

 manubrium refers a stimulus applied anywhere in 

 the mutilated nectocalyx to the band of tissue by 

 which it is still left in connection with that organ ; 



