SECTION OF NAKED-EYED MEDUSA. 115 



margin irritated as before, the manubrium would 

 be able to localize better than if, as before, the 

 radial distance between A B and c, d, e, f were less. 

 The greater this radial distance, the better would 

 be the localizing power of the manubrium ; so that, 

 for instance, if the cut A' B' were situated nearly 

 at the base of the manubrium, the latter orofan 

 might be able to localize correctly a stimulus ap- 

 plied, not only as before at /, but also at e or d. In 

 such comparative experiments, however, it is to be 

 understood that the higher up in the bell a cut is 

 placed, the shorter it must be ; for a fair comparison 

 requires that the two ends of the cut shall always 

 touch the same two radii of the nectocalyx. Still, 

 if the cut is only a very short one (say one or two 

 millims. long), this consideration need not practically 

 be taken into account ; for such a cut, if situated 

 just above the margin, as represented at a, will 

 have the effect of destroying the localizing power of 

 the manubrium as regards the corresponding arc of 

 the margin; but if situated high up in the bell, 

 even though its length be still the same, it will not 

 have this effect. 



From all this, then, we have seen that the con- 

 nections which render possible the accurate localiz- 

 ino^ functions of the manubrium are almost, though 

 not quite, exclusively radial. We have also seen 

 that between accurate localization and mere random 

 movements on the part of the manubrium there are 

 numerous gradations, the degree of decline from 

 one to the other depending on the topographical 

 relations between the point of stimulation and the 



