44 ANIMAL INDIVIDUALITY [CH. 



comparable with a protozoan 1 . When the method is 

 traced by which the plurality of cells in the adult 

 arises from the single cell of the egg the method, 

 that is, of cell-reproduction it is found to be identical 

 with one of the ways of reproduction in metazoan 

 individuals, that of fission ; the single founder of the 

 cell-community, the egg, divides the whole of its 

 substance into two halves, each of which is a new 

 cell. This is repeated again and again, and the whole 

 army of cells in the full-sized hydroid are direct 

 descendants of that single founder-cell. But the 

 hydroid is itself a founder ; and the new "individuals" 

 which it buds out depend for their growth upon this 

 same process of cell-division continually repeated. 



The paradox is growing yet. Each hydroid seems 

 in its way a whole ; yet it is as well a mere part of a 

 single greater whole, the colony, and, besides this, 

 itself composed of units each of which again is in 

 some sort a whole : and each whole has some claim 

 to the name of Individual. 



One gap still yawns : what was the origin of the 

 single cell that gave birth to the whole adult organism? 

 In this particular case, it was a fertilized ovum : by 

 which is implied that the single cell has arisen from 

 the total fusion, body and soul, or rather cytoplasm 



1 The animal kingdom is divided into the two primary sub- 

 kingdoms Protozoa or single-celled animals, and Metazoa or many- 

 celled animals. 



