HYDRAID^ : HYDRA. 131 



of their untoward position, from which they are frequently libe- 

 rated by the opportune break of the worm, when each obtains his 

 share ; but should the prey prove too tough, woe to the unready ! 

 The more resolute dilates the mouth to the requisite extent, and 

 deliberately swallows his opponent, sometimes partially, so as, how- 

 ever, to compel the discharge of the bait, while at other times the 

 entire polype is engulphed ! But a polype is no fitting food to a 

 polype, and his capacity of endurance saves him from this living 

 tomb ; for after a time, when the worm is sucked out of him, the 

 sufferer is disgorged with no other loss than his dinner.* This fact 

 is the more remarkable when it is contrasted with the fate which 

 awaits the worms on which they feed. No sooner are these laid 

 hold upon than they evince every symptom of painful suffering ; but 

 their violent contortions are momentary, and a cei'tain death sud- 

 denhj follozvs their ca^yture. How this effect is produced is still 

 matter of conjecture. Worms, in ordinary circumstances, are most 

 tenacious of life, even under severe wounds ; and hence one is in- 

 clined to suppose that there must be something eminently poi- 

 sonous in the Hydra's grasp. "I have sometimes," says Baker, 

 '' forced a worm from a polype the instant it has been bitten (at the 

 expense of breaking off the polype's arms), and have always observed 

 it to die very soon afterwards, without one single instance of re- 

 covery."t To the Entomostraca, however, its touch is not equally 

 fatal ; for I have repeatedly seen Cyprides and Daphnije, entangled in 

 the tentacula and arrested for some considerable time, escape even 

 from the very lips of the mouth, and swim about afterwards un- 

 harmed — their shell evidently protecting them from the poisonous 

 excretion. The grosser parts of the food, after some hours' di- 



* Trembley, Mem. 112. 



t Hist, of the Polype, 33 — comp. with 67-8. — " That insignificant and inactive 

 insect called the fresh-water polypus, of all poisonous animals, seems to possess the 

 most powerful and active venom. Small water-worms, which the polypus is only 

 able to attack, are so tenacious of life, that they may be cut to pieces without their 

 seeming to receive any material injury, or to suffer much pain from the incisions. 

 But the poison of the polypus instantly extinguishes every principle of life and 

 motion. What is singular, the mouth or lips of the polj-pus have no sooner touched 

 this worm than it expires. No wound, however, is to be perceived in the dead 

 animal. By experiments made with the best microscopes, it has been found that tlie 

 polypus is neither provided with teeth, nor any other instrument that could pierce 

 the skin." Smellie's Phil, of Nat. History, ii. 402.— The fact that fishes cannot be 

 made to swallow Hydrae, seems to prove the presence of some irritating quality in the 



latter. See Trembley, Mem. 137. 



k2 



