SOME MOOT POIXTS IX XATURAL HISTORY. 269 



margin of the body is cut off, the amputated portion, as 

 will hereafter be described, will continue to move for days 

 in its independent state. That sea-anemones are sensitive 

 to impressions of much more delicate nature than touch, is 

 proved by the fact familiar to all aquarium-keepers, that 

 the sudden obstruction of the light which has been playing 

 on the tentacles will cause their retraction and withdrawal. 

 The sensitiveness of these and like animals is very naturally 

 referred to the presence of nerves ; but it is a most note- 

 worthy fact that but few traces of nerves have been dis- 

 covered in sea-anemones after the most careful research ; 

 and if nerve-filaments exist in the still lower jelly-fishes, they 

 must be present in a condition of the most primitive and 

 rudimentary nature. Whilst in the equally sensitive hydrse 

 (Fig. 38) and other polypes, no traces whatever of a nervous 

 system can be perceived. 



Hence we find that veritable animals, of which the 

 anemones and their lower neighbours are examples, exhibit 

 a delicate sensitiveness, notwithstanding the absence of 

 demonstrable nerve-fibres. After the recital of this fact it 

 can hardly be maintained with reason that the absence of 

 nerves in plants affords any reasonable grounds for the 

 opinion that sensation in the vegetable world is something 

 different from the sensitiveness of animals. The considera- 

 tion of facts like the preceding, forces us thus to the con- 

 clusion that animals and plants are endowed with a common 

 sensibility of very varying degrees of perfection ; and that, 

 judging from analogy, the apparatus whereby this sensitive- 

 ness is exercised in the one group of living beings does not 

 materially differ from that excercising this quality in the 

 other. Whilst the subject also shows us the impossibility of 

 distinguishing between animals and plants in respect of 

 sensation and its results, and also tends to strengthen the 

 belief that the primitive form of a nerve is simply that of a 

 specially modified line or tract in the bodies of lower animals 

 and plants connecting two points of the body, and capable 

 of inducing, through such communication, changes of a more 



