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



one of these open enrls, the fluid of course permeates 

 the ^vhole tube, and the contraction-wave becomes 

 blocked at tlie transverse line occupied by the tube 

 as effectually as if the contractile strip had been cut 

 through at that line. 



A glance at Fig 10, again, will show that each 

 lithocyst is surrounded by one of these nutrient 

 tubes. Upon injecting this tube, therefore, in a 

 contractile strip, the effect of the poison may be 

 exerted on the lithocyst more specially than it 

 could be by j-ny other method of administration. 

 In view of recent observations concerning the effects 

 of curare on the ccntial nervous masses of higher 

 animals, it may be worth while to state that a dis- 

 charging lithocyst of Aurelia aurita, when thus 

 injected with curare, speedily ceases its discharges. 

 This fact alone, however, would not warrant any 

 very trustworthy conclusions as to the influence of 

 curare upon discharging centres ; for it is not im- 

 probable that the paralyzing effects may here be 

 due to the influence of the poison on the surround- 

 inor contractile tissue. 



o 



It is interesting to observe that if the discharging 

 lithocyst be injected with chloroform, or a not too 

 strong solution of morphia, it recovers in the course 

 of a ni'dit. With alcohol the first effects of , the in- 

 jection are considerably to accelerate the frequency 

 and to augment the potency of the discharges; but 

 the subsequent effects are a gradual diminution in 

 the frequency and the vigour of these discharges, 

 until eventually total quiescence supervenes. In the 

 course of a few hours, however, the torpidity wears 



