110 THE NATURE AND VARIETIES OF 



and phytoids in that of plants, as indicating that any one 

 of them is not so much a complete animal or plant in 

 itself, as a fragment or fractional part of one the whole 

 series, considered as specific unit, rather than any one 

 among the successive links of which it is made up, answer- 

 ing to our idea of individual completeness, as this is drawn 

 from the higher animals, in which like seems always to 

 produce like. 



In confirmation of such a view, it is noticed that in not 

 a few cases these fractional phytoids and zooids really re- 

 main in organic union for life making up an arborescent 

 form like what we call a polypidom in animals, which is 

 readily recognized as being in its entireness the individual 

 representative of the species. 



In this view zoological individuality becomes a very dif- 

 ferent thing from metaphysical individuality,* for organs, 

 which in one species are integrally united into a whole 

 which is indivisible without mutilation, are found in others 

 more or less broken up into separate and independent 

 structures. Hence if we would avoid the solecism of speak- 

 ing of the individual, as in some cases being divided into a 

 number of parts, having all a general character of com- 

 pleteness, and use the word, as propriety seems to require, 

 in its logical sense of that which is individualized, we must 

 be prepared to admit as a consequence, that the individuals 

 of one species are not always homologous with those of 

 another.-)- 



But though we may allow so much in common in 

 these cases of " alternation," as is involved in the occur- 

 rence in all of a periodic diversity of derived forms, there 

 are y e t as was pointed out in the introductory chapter 

 o-reat variations among them, as far as the relations are 



* Huxley in Philos. Transactions for 1851. Paper on Salpw, p. 579. 

 f Mr. Lubbock in Philosophical Transactions. Jany. 29, 1857. 



