114 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 



probably be so far able to localize the seat of irrita- 

 tion as to confine its movements, in its search for the 

 offending body, to perhaps the quadrant of the bell 

 in which the stimulation is being applied. If the 

 stimulation be now supplied at e, the localization 

 on the part of the manubrium will be still more 

 accurate ; and if applied at /(that is, almost beneath 

 one end of the cut A B), the manubrium may suc- 

 ceed in localizing quite correctly. 



These facts may also be well brought out by 

 another mode of section, viz. by cutting round a 

 greater or less extent of the marginal tissue, leaving 

 one end of the resulting slip free, and the other end 

 attached in situ. If this form of section be 

 practised on Tiaropsis indicans, as represented at 

 g k in the figure, it may also be observed that 

 irritation of a distant point in the marginal strip, 

 such as g or h, causes the manubrium to move in 

 various directions, without any special reference to 

 that part of the bell which the irritated point of 

 the marginal strip would occupy if in situ. But if 

 the stimulation be applied only one or two millims. 

 from the point of attachment of the marginal strip, 

 as at i, the manubrium will confine its localizinof 

 motions to perhaps the proper quadrant of the bell ; 

 and if the stimulus be applied still nearer to the 

 attachment of the severed strip, as at^', the localizing 

 motions of the manubrium may become quite 

 accurate. 



Asrain, wdth reirard to radial distance, if the cut 

 A B in the figure were situated higher up in the 

 bell, as at A' B', and the arc, c, d, e, f, of the 



