ANATOMY AND DEVELOPMENT OF THE ECHINODERMS II7 



We propose on the other hand not to alter the ordinary zoological 

 meaning of the word " individuality," but merely to define it more 

 strictly, and gi\e to it the relative value of the attributes which it 

 ■connotes, and which are conversely a mark of it. 



Individuality has so long and so obviously, among the higher 

 animals, been observed to be accompanied by independent existence, 

 that the latter attribute has come to be considered as, conversely, an 

 indication of individuality — to the neglect of the really characteristic 

 attribute, which is — the circumstance of being the total result of the 

 development of a single ovum. 



According to our view, then, the zoological individual = the total 

 result of the development of a single ovum, whether this total result con- 

 sist of one or many independent existences. The individual is the 

 zoological unit, and its value is the same, whether we have it as (i) or 

 ^s (g + 3^ + ^). A fraction does not become equal to the unit by 

 standing alone. The Cyanasa and the Polype from which it proceeds, 

 the two forms of Salpa;, the parent nurses, nurses, and Cercariai, of the 

 Distomata, are not distinct individuals — are not separately equivalent 

 to an individual beetle or dog. 



It is their sum only which is equivalent to the individual among 

 the higher animals. 



They are not the individual, but are successive forms by which the 

 individual is manifested ; standing in the same relation to the indi- 

 vidual, as the incarnations of Vishnu to Vishnu, in the Hindoo 

 theology. 



What then may these independently existing " parts of indi- 

 viduals " be properly termed ? They can hardly be called organs 

 without doing violence to our ordinary acceptation of the nature of an 

 •organ, in which a certain subserviency and dependence is understood. 

 The term " sooid" has been devised; and as it has no theoretical 

 meaning, but is merely intended to suggest two indisputable facts 

 with regard to the creatures to which it is applied — namely that they 

 are like individuals, and yet are not individuals, in the sense that one 

 of the higher animals is an individual — its use does not appear to be 

 open to any serious objection. 



Instead of saying then, that in a given species, there is an alterna- 

 tion of so many generations, we should say that the individual consists 

 of so many zooids. 



Again, where no " alternation " takes place, the individual = the 

 sum of its organs ; where there is alternation, the individual = the 

 5um of its " zooids." 



If the view we have taken be correct, the whole doctrine of the 



