DEGRADATION OF ORGANISATION 101 



reproduction. Now in order to produce true eggs, it is necessary not 

 only that the animal should have an ovary, but in addition that it or 

 some other individual of its species should have a special organ for 

 fertilisation, and it cannot be shown that the polyps have such organs ; 

 in place of them we are well aware of the buds which some of them 

 produce for purposes of multiphcation ; and on paying them a Uttle 

 attention we note that these buds are themselves nothing more than 

 somewhat isolated portions of the animal's body, — portions less 

 simple than those employed by nature for the multiplication of the 

 animalcules which compose the last class of the animal kingdom. 



Polyps, being highly irritable, only move by external stimuli foreign 

 to themselves. All their movements are necessary results of impressions 

 received, and are in general carried out without any act of will ; they 

 are thus without any possibility of choice, since they cannot have 

 any will. 



They invariably and inevitably move towards the Hght, just like 

 the branches and leaves or flowers of plants, although in their case the 

 movement is slower. No polyp pursues its prey, nor seeks for it with 

 its tentacles ; but when some foreign body touches these same ten- 

 tacles, they hold it and carry it to the mouth, and the polyp swallows 

 it without making any distinction as to its suitability or the reverse. 

 It digests and feeds on the body if it is capable of being digested, 

 but rejects it entirely if it remains some time untouched in the 

 alimentary canal ; finally, it brings up such of the debris as can be no 

 more broken up ; but in all this, there is the same necessity in the 

 action and never any possibihty of choice to vary it. 



The distinction of the polyps from the radiarians is very wide and 

 glaring ; nowhere in the interior of the polyps is the radiating arrange- 

 ment to be found : their tentacles alone have this arrangement, thus 

 resembhng the arms of the- cephalapod molluscs, with which however 

 they certainly cannot be confused. Moreover the polyps have a 

 superior terminal mouth, while the mouth of the radiarians is other- 

 wise situated. 



It is altogether improper to give the polyps the name of zoophytes, 

 which means animal-plants ; because they are entirely and completely 

 animals. They have faculties absent in plants, that, for instance, of 

 true irritablity and generally of digestion ; and, lastly, their nature 

 has nothing essentially in common with that of a plant. 



The only affinities existing between polyps and plants are : (1) A 

 similar simplification of organisation ; (2) the faculty possessed by 

 many polyps of adhering to one another with a common conmunica- 

 tion by their ahmentary canal, and of forming compound animals ; 

 (3) the" external shape of the groups formed by these combined polyps, 



