COSMIC PHILOSOPHY 



occurs in the spider, the bee, and the butterfly. 

 In contrast with this, we may profitably observe 

 what goes on in many annuloid worms, where 

 the multiplication of segments by differentia- 

 tion results in the fission of the animal into 

 two distinct individuals, because the integrating 

 power of the organism is slight. 1 Similarly in 



1 Here, without prejudice to the general argument, I may 

 call attention to the very ingenious hypothesis propounded by 

 Mr. Spencer, to account for the origin of the annulose or 

 articulated sub-kingdom of animals. According to this hypo- 

 thesis, any annulose animal is in reality a compound organism, 

 each of its segments representing what was originally a distinct 

 individual. In other words, an annulose animal is a colony or 

 community of animals which have become integrated into an 

 individual animal. Strong prima facie evidence of such a linear 

 joining of individuals primevally separate is furnished by the 

 structure of the lowest annelids. Between the successive seg- 

 ments there is almost complete identity, both internal and 

 external. Each segment is physiologically an entire creature, 

 possessing all the organs necessary for individual completeness 

 of life ; not only legs and bronchiae of its own, but also its 

 own nerve-centres, its own reproductive organs, and frequently 

 its own pair of eyes. In many of the intestinal worms each seg- 

 ment has an entire reproductive apparatus, and being herma- 

 phrodite, constitutes a complete animal. Moreover in the devel- 

 opment of the embryo the segments grow from one another by 

 fission or gemmation, precisely as colonies of compound animals 

 grow. At the outset the embryo annelid is composed of only 

 one segment. The undifferentiated cells contained in this seg- 

 ment, instead of being all employed in the formation of a 

 heterogeneous and coherent structure within the segment, as 

 would be the case in an animal of higher type, proceed very 

 232 



