OBSERVATION AND EXPERIMENT. 161 



slightest indication of their being more incommoded 

 by the filaments than they wonld have been by threads 

 of silk. Mr Gosse, indeed, not only maintains that 

 these filaments are weapons of off'ence, but he actually 

 suggests that the blue sj^herules which surroundthe 

 disc of the Mesembryanthemum may " represent the 

 function of these missile filaments" because they are 

 composed of the thread-capsules. 



The hypothesis which assigns to the thread-capsules 

 a function of urtication, or prehension, is an hypothesis 

 without a single fact to warrant it, and is contradicted 

 by the various facts I have just adduced. Ehrenberg 

 has very unwarrantably given an ideal figure of a 

 Hydra in the act of seizing its prey, with the hooks of 

 the thread-cell extended ; but, as Siebold truly remarks, 

 the animal is never seen thus. 



Having sho^^^l that the parts most abundantly sup- 

 plied vdth these " urticating cells " do not urticate, I 

 can now remove the last vestige of doubt by the fact 

 that the capsule itself from the tentacle of an Anemone, 

 when seen to eject the thread and touch an animalcule, 

 does not kill or disable that animalcule ; a fact I wit- 

 nessed when examining the capsules under the micro- 

 scope. This not only gives the coup-de-grace to the 

 general hypothesis, but even sets aside that suggestion 

 of Professor Owen's respecting the probable superaddi- 

 tion to the " urticatino; cell" which is to distino-uish it 

 from " cells " in those parts destitute of the power ; 

 because here we see the capsule taken from an urticat- 

 ing animal does not urticate. 



