LOCOMOTION OF THE ANEMOXE. 131 



there is abundance of invisible aliment, — infusoria, 

 spores, organic j^articles, &c., which the animal assimi- 

 lates, much in the same way as plants assimilate the 

 organic material diffused through the soil and atmo- 

 sphere. Filter the water carefully, and remove from it 

 all growing vegetation, and you will find the animal speed- 

 ily dying, however freely oxygen may be supplied. It is 

 on this account that when we make artificial sea- water, 

 it is necessary to allow alga3 to grow in it for some 

 two or three weeks before putting in the animals ; the 

 water becomes charoed with oro-anic material. 



Mere sensibility and capture of food, therefore, are 

 not the distinguishing marks we seek, since the plant 

 is found to possess them as perfectly as the animal. 

 Is spontaneous locomotion a sufficient mark ? No ; and 

 for these two reasons : Some animals have ?io such 

 power ; some plants, and all spores, have it. There are - 

 animals which no botanist has ever claimed — the 

 Ascidians, for example, which can scarcely be said to 

 exhibit any motion at all (the rhythmic contraction and 

 expansion of their orifices not deserving the name) ; 

 their whole lives are spent rooted to the rock or shell, 

 as firmly as the plant is rooted in the earth. Nay, 

 even with regard to the Anemones, it is said by Dr 

 Landsborough, Dr Carpenter, and others, that they 

 will not move towards the water, should the vessel be 

 gradually emptied, or the water evaporate, not even if 

 their tentacles can reach its surface. This is incorrect ; 

 but I mention it as one of the difficulties which would 

 meet the student in the way of distinguishing the 



