HIGHER PLANTS AND ANIMALS. 317 



cycles of the past, the geologist is surely entitled to pre- 

 sume that a similar evolution will continue to mark the 

 onward course of creation. 



It is true, it may be argued, and indeed has been argued, 

 that the system of Life has culminated in the present 

 epoch, and is, consequently, subject to no further develop- 

 ment; and if it has not so culminated, that new races ought 

 now and then to be making their appearance. Such rea- 

 soning, however, is altogether at variance with the slow 

 and gradual evolution of events as impressively taught by 

 Geology. During the past, well-defined genera and orders 

 make their appearance only after the lapse of ages; and two 

 thousand or twenty thousand years of the current epoch 

 may be too short a period for the full development of new 

 and higher races. All that seems necessary for our argu- 

 ment is, that physiology can prove a tendency to variations 

 in existing genera and species ; and if such a tendency can 

 be demonstrated, no matter how slight and slow, the widest 

 subsequent divergence, even to the extent of new families 

 and orders, is only a question of time and continuation. 

 This is all that Geology contends for; and surely the varia- 

 tions in plants and animals which are continually taking 

 place under change of external condition, and under the in- 

 fluence of culture and domestication, must be sufficient to 

 convince every mind capable of ordinary reasoning, that 

 the susceptibility to newer developments is a quality as 

 operative now as during any of the former epochs. It is 

 vain to argue that no introduction of newer forms has been 

 witnessed during the last three or four thousand years of 

 human history. It is little more than half a century since 

 such questions began to attract the attention of philoso- 

 phers ; and all that went before erroneous notions of nat- 

 ural history, limited acquaintance with the geography of 

 the world, ignorance of geology, and total absence of all 



