56 DUHLIN UNIVERSITY 



Suppose that, into a vessel containing somo Actinia well expanded, 

 and apparently on the look-out for food, some of the tadpoles of the 

 common frog be introduced, these little creatures do not, like many fresh- 

 water fishes of about the same dimensions, immediately die ; on the con- 

 trary, the salt water seems to stimulate them to activity, they become 

 very lively, and swim about with vivacity. One of them may not un- 

 frequently bo observed to make its way among the tentacles of an Actinia 

 and get away again quite uninjured; it may even for a time nestle 

 among the tentacles with as much impunity as if it were only in contact 

 with a piece of sea-weed. But should the tadpole have the misfortune 

 to fall in with a more voracious Actinia, the reception it meets with is 

 very different : sometimes by an incautious lash of its tail it may touch 

 even a single tentacle, by which it is at once laid hold of, and in the 

 violent efforts which it forthwith makes to break loose often merely 

 brings itself within the reach of other tentacles, by which it is seized 

 and overpowered. Occasionally, however, after having been thus seized, 

 the tadpole, by its superior activity, succeeds in effecting its escape, and 

 when it does so, it seems for a time singularly excited ; it twists, and 

 writhes, and wriggles through the water, so as to leave no doubt that 

 some very remarkable influence has been exerted upon it. 



These observations arc, no doubt, familiar to all who have studied 

 the habits of these animals ; for, although the tadpole seems more sus- 

 ceptible of the peculiar stimulus which the Actinia can communicate 

 than most of those creatures which are ordinarily cast in its way, yet 

 the same occurrences take place with the smaller Crustacea, &c, which 

 are abundant in sea-water. Indeed, no very close attention is necessary 

 to perceive that, while on some occasions these little creatures may creep 

 to and fro over the surface, and among the tentacles of the Actinia, at 

 other times they are seized and killed with the greatest promptitude. 



It remained to be determined what is the exact nature of the power 

 which the Actinia has been thus found to have under its control. If it 

 seized its victim by a simply mechanical effort, why should the tadpole 

 be so agitated for some time after having escaped from its grasp ? 



No peculiarly viscid secretion could be detected on the tentacles, nor 

 could any decided reaction be discerned on their surface differing from 

 the feebly alkaline condition of the sea water in which they were placed ; 

 moreover, the power of the Actinia seemed often to be exerted with too 

 much promptness to be compatible with the notion of the formation of 

 a poisonous or stinging fluid over its surface. 



