14 Prof. Miiller on the Anatomy and Development 



Now the questions to be decided before the alternation theory 

 can be said to apply to the Echinoderms or any other animals, 

 are different as regards the two portions of the theory. The 

 problem as regards the first question is a matter of naming — as 

 regards the second it is a matter of fact. 



We have said that the question involved in the first part of 

 the theory is a question of naming. It is, whether we can apply 

 to A, 13, C, &c. in the foregoing instance, the name " indivi- 

 dual." For it is quite clear that if they cannot with propriety 

 be called " individuals," their succession cannot be called an 

 u alternation of generations," inasmuch as generations are com- 

 posed of individuals. 



We must carefully bear in mind that this inquiry has nothing 

 to do with the thorny problem of psychical individuality. With 

 that the zoologist has no concern ; his science investigates the 

 laws of animal form, and in psychological questions he has no 

 more direct interest than the astronomer has in the zoology of 

 the planet Saturn. 



Leaving psychological considerations aside, then, and inquiring 

 into the zoological meaning of the term " individual," we find that 

 anything to which it is applied among the higher and the greater 

 part of the lower animals, has two principal characters : first, it 

 has an independent existence ; and secondly, it is the total result 

 of the independent development of a single ovum. 



Now the forms A, B, C, described as " individuals " by Steen- 

 strup, have only one of these characters (in the most strongly 

 marked cases of " alternation "), that of independent existence ; 

 for each of them is only part of " the total result of the develop- 

 ment of a single ovum." 



But in predicating " individuality " of any animal which does 

 not " alternate," we predicate both these characters of it. 



Hence, unless the meaning of the term " individual " be al- 

 tered, the advocates of the alternation theory commit the capital 

 error of using the same term in two very different senses, accord- 

 ing as they speak of a Hydra or a Campanularia, a Salpa or a 

 Cynthia. 



It is only by narrowing the meaning of the word " individual " 

 to mere " independent existence," that it can possibly become 

 applicable in Steenstrup's sense. But in this case spermatozoa, 

 spermatophora, and even cancer cells, would equally be " indivi- 

 duals." So that the new meaning would be not only entirely ar- 

 bitrary, but opposed to the general sense of zoologists. 



We propose on the other hand not to alter the ordinary zo- 

 ological meaning of the word " individuality," but merely to de- 

 fine it more strictly, and give to the relative value of the attributes 

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



