EVOLUTIONS OF ORGANIZATION. 5 



that ; and if I confine my view to the animal 

 kingdom, I think the days are past when any one 

 will consider it chimerical to compare vertebrates 

 with invertebrates, or the most dissimilar inverte- 

 brates one with another. At once it will be granted 

 that ova, however various, are comparable, and 

 that it is matter for observation to compare the 

 stages of their growth as they give rise to forms 

 that are far asunder. Nor will any serious doubt 

 be entertained on survey of that highest and most 

 important assemblage of animals the vertebrata, that 

 they have appeared on earth in the order of their 

 complexity ; however great may be the mystery in 

 which the rise of invertebrata may be wrapped. 

 All this involves the conception of a complex unity 

 acquiring its complexity stage by stage, even as 

 the individual develops from the ovum to the adult 

 condition ; and such a conception may be justly 

 termed Evolution. 



But such an evolution may be conceived of 

 variously, both in respect of character and cause. 

 In its character it may be conceived of as a growth 

 without aim, forming altogether an indefinite ag- 

 gregation like the sum of the branches of a tree ; 

 or the view may be held that it is an orderly 

 arrangement, like some vast temple in which every 

 minaret and most fantastic ornament has got its 



