071 some Mamie Afiimals a?id Plants, 32^ 



fore the animals had died of suffocation. Pennant states 

 that the torpedo dies in fresh water almost as soon as in the 

 open air ; but I had already ascertained that these worms will 

 remain in air for many hours, without seeming to suffer any 

 inconvenience. 



I had a number of specimens lying on a plate motionless ; 

 for, unless disturbed, they are little inclined to move. I dipped 

 my hand in fresh water, and with a jerk, sprinkled some drops 

 of it over the plate, and the specimens on it. In about two 

 seconds the worms were all in violent agitation, rolling round 

 on the longitudinal axis of their bodies, and writhing together 

 in apparent agonies. After a few minutes ihe agitation 

 ceased, and they again lay motionless. I now tried the effect 

 of touching an individual with a small drop of fresh water. 

 The part to which the latter was applied, almost immediately 

 contracted in the manner that a leech contracts at the place 

 where a little salt is applied to it, and then, the whole animal 

 became agitated and dashed violently about the plate, fre- 

 quently, at the same time, protruding and contracting its pro- 

 boscis. Similar effects followed every trial I made, and it 

 mattered not what part of the animal was touched ; the smallest 

 drop of water from the point of a probe produced the partial 

 contraction at the part, and then the general convulsive 

 writhing and agitation of the whole body. Even fragments of 

 the worm were similarly affected. It appeared to me, how- 

 ever, that the mouth extremity was more sensible to the touch 

 of the poison than any other part, as the convulsive efforts 

 which followed seemed more violent, and longer continued 

 than when the water was applied elsewhere. 



I made similar trials on many of these animals, and invari- 

 ably found the same results. The most striking way of ex- 

 emplifying the virulent effects of fresh water is, when the 

 worm is at rest to apply consecutively from the point of a 

 probe ten or a dozen small drops of sea water to any part of 

 it, this causes no alteration ; the animal continues motionless. 

 If we then change the drop to be applied from salt to fresh, 

 the very first application of the latter immediately produces 

 the phenomena above described. 



In whatever way it is that fresh water proves so poisonous 

 and fatal to this species, one thing is obvious, that the animal 

 can never propagate except under the influence of sea water. 

 It can never colonise rivers or lakes, and the subject, if farther 

 pursued by experiments on other species, may, perhaps, throw 

 some light on the distribution of animals. The Lurg-worms 

 cannot even safely inhabit those parts of the shore which are 

 long uncovered by the sea; a heavy shower of rain during 



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