76 LIFE AND ORGANISATION. 



types of structure, declaring to our reason the unity of the 

 creating cause, but evolved under many and singular diver- 

 sities of form ; with the special fact superadded that each 

 epoch contains species peculiar to itself. Different species 

 more or less approximate to each other ; but in none of these 

 periods have we yet found any such series as to indicate an 

 actual passage from one to another ; or anything more than 

 this proximity, itself expressed in all cases by the same 

 special forms and relations of parts. 



There is, however, one point of connection beween these 

 periods, which bears in some sort on the question before us. 

 We allude to the fact indisputable in itself, and deeply 

 interesting in all ways of the successive appearance of 

 higher types of organisation and conditions of existence, in 

 rising from the earliest of these epochs to that in which we 

 have our own being. We shall revert to this topic hereafter, 

 and notice it here only to show that it does not sanction, or 

 even favour, the doctrine of transmutation. There is no 

 regular gradation either as to time or type, such as the theory 

 would require. New and higher forms of life come in with 

 new epochs, and continue to be associated with the lower 

 types that before existed. Kecent research has carried back 

 some of these higher forms into geological ages more remote 

 than was once supposed their limit; and this may go yet 

 further. But it would not then, more than it does now, 

 affect the argument we are holding. 



The existence of such common types or plans of structure, 

 extending throughout the whole domain of life and giving 

 foundation to all special forms and varieties, may seem at 

 first sight to furnish some valid argument for transmutation ; 

 and the more so since these types are found in one sense to 

 graduate into one another. The individuals of higher type 

 throughout the several great groups of the animal kingdom, 

 pass through certain stages of those lower in the scale, 



