106 JELLY-FISH, STAR-FISH, AND SEA-URCHINS 



more locomotor contractions. If in the latter case 

 the stimulus be not too strong, or, better still, if the 

 specimen operated on be in a noii-vigorous or in 

 a partly ansesthesiated state, it may be observed 

 that a short interval elapses between ihe response 

 of the tentacles and that of the bell. Lastl}^, the 

 manubrium is much more sensitive to a stimulus 

 applied to a tentacle, or to one of the marginal 

 bodies, than it is to a stimulus applied at any other 

 part of the nectocalyx. 



These facts clearly point to the inference that 

 nervous connections unite the tentacles with one 

 another and also with the manubrium ; or, perhaps 

 more precisely, that each marginal body acts as 

 a co-ordinating centre between nerves proceeding 

 from it in four directions, viz. to the attached 

 tentacle, to the margin on either side, and to the 

 manubrium. This, it will be observed, is the distri- 

 bution which Haeckel describes as occurring in 

 Geryonia, and Schultz as occuriing in Sarsia. It is, 

 further, the distribution to which m}^ explorations 

 by stimulus would certainly point. But, in order 

 to test the matter still more thoroughly, I tried the 

 effects of section in destroying the physiological 

 relations which I have just described. These effects, 

 in the case of the tentacles, were sufficiently precise. 

 A minute radial cut (only just long enough to 

 sever the tissues of the extreme margin) introduced 

 between each pair of adjacent marginal bodies 

 completely destroyed the physiological connection 

 between the tentacles. If only three marginal cuts 

 were introduced, the sympathy between those two 



