X.] THE COMMON FROG. 157 



and latent till made manifest, through the advent of 

 conditions so obscure that as yet they have evaded 

 the most careful and anxious scrutiny of practised 

 adepts. 



It would seem to be a negligence not here to point 

 out, that if new forms of life — new species — arise from 

 time to time through congenital variation, not a few of 

 the facts herein quoted point to the probability that 

 such forms have arisen through the evolutions of im- 

 planted potentialities definite in nature, in other words, 

 by ^' specific genesis." 



Again, a general survey of the diff'erent kinds of re- 

 lations which the Frog has brought before us is well 

 calculated to impress us with the overwhelming rich- 

 ness and fulness of nature. 



Although, from our ignorance, the natural history 

 of many other animals well known to us may appear 

 less replete with interest than that of the common 

 Frog may now be, yet it cannot be doubted but that 

 the progress of science is capable of revealing to us 

 facts as full of instruction, and of as profound a signi- 

 ficance in the life history of almost any kind of animal 

 whatever. 



Ever fresh, ever fertile, natural history offers to our 

 faculties a pursuit practically inexhaustible. We are 

 not, indeed, denied the gratification of successfully 

 exploring and satisfactorily explaining mystery after 

 mystery, but each secret wrested by our efforts brings 

 before us other ever-new enigmas, so that though 

 refreshed by success we need never be wearied by 

 monotony. While we need not regard any problem 

 as absolutely hopeless, no dread of coming to the 



