266 SYMBIOGENESIS 



How else could we account for the unlikenesses of different 

 organisms, all of which are composed of these atoms? If the 

 polarities of the chemical atoms determined organic form, 

 how could we account for the occurrence of such endlessly 

 varied forms as nature presents? Hence Spencer postulates 

 his " physiological " units as the ultimate agents of form. 

 We have seen from the case of plantagens that the power of 

 reproduction of organic form depends in reality on the 

 presence of individuality, and we must suspect that it is a 

 similar kind of individualised unit which is at the base of 

 form. Such units we have already seen to change according 

 to bio-economic specialisation, i.e.. they are responsive and 

 responsible, though primitive, members of the biological 

 world. 



The question of individuality is broached in Spencer's 

 special chapter on that subject, when the conclusion is reached 

 that no definition of individuality is unobjectionable, and that 

 ' ' we must be content with a course which commits us to the 

 smallest number of incongruities." 



Something seems to be gained by restricting the application of the 

 title individual to organisms which, being in all respects fully 

 developed, possess the power of producing their kind after the ordinary 

 sexual method ; and denying this title to those incomplete organisms 

 which have not this power. But the definition does not really establish 

 this distinction for us. On the one hand, we have cases in which, as 

 in the working bee, the whole of the germ-product is aggregated into a 

 single organism ; and yet, though an individual according to the defini- 

 tion, this organism has no power of reproducing its kind. On the other 

 hand, we have cases like that of the perfect Aphides, where the organism 

 is but an infinitesimal part of the germ-product ; and yet has that 

 completeness required for sexual reproduction. Moreover, if we adopt 

 the proposed view, we find ourselves committed to the anomalous position, 

 that among many orders of animals there are no concrete individuals 

 at all. If the individual is constituted by the whole germ-product, 

 whether continuously or discontinuously developed, then, not only must 

 individuality be denied to each of the imperfect Aphides, but also to 

 each of the perfect males and females; since no one of them is more 

 than a minute fraction of the total germ-product. And yet further, it 

 might be urged, with some show of reason, that if the conception of 

 individuality involves the conception of completeness, then, an organism 

 which possesses an independent power of reproducing itself, being more 



