238 JELLY-FISH, STAR-FISH, AND SEA-UHCHINS. 



Physiological Effects of Fresh Water on the Mecliiscc 



As fresh water exerts a very deadly int^ucnce on 

 the MedusfB, this seems the most apj)ropriate place 

 for describing its action. Such a description has 

 already been given by Professor L. Agassiz, but it 

 is erroneous. He writes, "Taking up in a spoon- 

 ful of sea- water a fresh Sarsia in full activity, when 

 swimming most energetically, and emptying it into 

 a tumbler full of fresh water of the same tempera- 

 ture, the little animal will at once drop like a ball 



fact that after the poisonino: the neuro-muscnlar tissue oftec 

 behaved diffi-rontly towards different kinds of stimulation. 



Fui'ther, in the particular case of my experiments with curare — 

 against which Dr. Krukenberg's remarks are chiefly dii-ected on 

 the ground tliat I did not prove the paralysis to be a merely mus- 

 cular effect — I succeeded in obtaining very much better proof of 

 the poison acting on the nervous elements, to the exclusion of the 

 muscular, than I could have obtained by any process of inference, 

 however goot] ; that is to say, I obtained direct proof. It appears 

 to me that Dr. Krukenberg must have failed to understand the 

 English of the following sentences : " On nipping any portion of 

 the poisoned half of Staurophora laciniata, this half remained 

 absolutely motiotiless, while the uniioisoned half, ''hough far away 

 from the seat of irritation, innnediately ceased its normal con- 

 tractions, and folded itself together in the very peculiar and dis- 

 tinctive manner just described," i.e. "in one very strong and 

 long-protracted systole." For the rest, see note on page 232. 



Lastly, while again expressing my satisfaction that on all 

 matters of fact our results are in full harmony, I may be allowed 

 to remark that in my opinion his deductions, as embodied in his 

 schema of the inferred innervation of Medusaj, are very far in 

 advance of anything that is justified by observation. (See, for 

 this elaborate schema, in which there are represented volitional, 

 motor, reflex, and inhibitory centres, as well as a clearly defined 

 system of sensory and motor nerves, " Vergleichend-Physio- 

 logogische SLudieu, diitte Abtheiling," p. 141 : Ilcidelberg, 1880.) 



