l6 EX VIRIBUS VIVIMUS. 



objection. In the Vertebrata, in Mollusca, in most 

 Insects, such a definition is unobjectionable; but when 

 we consider the numerous examples of asexual re- 

 production we are led into difficulty. 'It seems a 

 questionable use of language to say that the countless 

 masses of Anacharis alsinastrum which, within these 

 few years, have grown up in our rivers, canals, and 

 ponds are all parts of one individual.' ^ And yet, as 

 this plant does not seed in England, these countless 

 masses, having arisen by asexual multiplication, must 

 be so regarded, if the above definition be accepted. 

 In the Hydrozoa are we to ascribe the same amount 

 of individuality to those forms which give rise to 

 separate polypidoms by the separation of budded 

 offspring, as to those to which these remain attached, 

 to form a compound polypidom .' The same difficulty 

 occurs with the lower Annelids and Vermes, with 

 Aphis, and such asexually proliferous insects, and 

 with multiaxial plants whose buds are capable of 

 separation and the initiation of distinct existences. 

 An illustration of the perplexity into which the above 

 definition of the individual would lead us in regard to 

 the question of longevity is furnished by such com- 

 pound organisms as are known among the Actinozoa. 

 ' Ehrenberg judges that certain enormous corals which 

 he saw in the Red Sea, and parts of which are still 

 tenanted by working polypes, were alive in the time of 

 the Pharaohs, and have been growing and enlarging 

 ' Spencer. 



