238 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
Physiological Effects of Fresh Water on the Meduscee 
As fresh water exerts a very deadly influence on 
the Medusz, this seems the most appropriate 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 poisoning the neuro-muscular tissue often 
behaved differently towards different kinds of stimulation. 
Further, in the particular case of my experiments with curare— 
against which Dr. Krukenberg’s remarks are chiefly directed on 
the ground that 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 good; 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 motionless, while the unpoisoned half, though far away 
from the seat of irritation, immediately ceased its normal con- 
tractions, and folded itself together in the very peculiar and dis- 
tinctive manner just described,’ te. ‘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 Medusz, 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 Studien, dritte Abtheiling,” p. 141: Heidelberg, 1880.) 
