THE VEGETABLE AND ANDIAL KINGDOMS. 143 



hovering over a pool for its one April day of life, were capable 

 of observing the fry of the frog in the water below. In its 

 aged afternoon, having seen no change upon them for such a 

 long time, it would be little qualified to conceive that the ex- 

 ternal branchiae of these creatures were to decay, and be 

 replaced by internal lungs, that feet were to be developed, the 

 tail erased, and the animal then to become a denizen of the 

 land. Precisely such may be our difficulty in conceiving that 

 the advance of plants and animals by generation to a higher 

 type of being is a possibility of nature. Granting that, 

 during the whole time which we call the historical era, there 

 have been no movements of this kind, nor even any of the less 

 rare transitions in which only specific modifications are con- 

 cerned, we know the historical era to be only an infinitesimal 

 portion of the entire age of our globe. We do not know what 

 may have happened during the ages which preceded its com- 

 mencement, as we do not know what may happen in ages yet 

 in the distant future. All, therefore, that we can properly 

 infer from the apparent fixity of organic forms is, that such is 

 the ordinary procedure of nature in the time immediately 

 passing before our eyes. Mr. Babbage's illustration enables us 

 to understand how this ordinary procedure may be subordinate 

 to a higher law which in proper season interrupts and 

 changes it. 



We have seen that gestation consists of two distinct and in- 

 dependent stages one devoted to the development of the new 

 being through the conditions of the inferior types, or, rather 

 through the corresponding first stages of their development ; 

 another perfecting and bringing the new being to a healthy 

 maturity, on the basis of the point of development reached. 

 It becomes very clear, that the protraction of the more general 

 condition, at some given stage, till a higher special point was 

 reached overleaping, as it were, the intermediate space is 

 all that is necessary for an advance from one grade of being to 

 another. 



We may never see an example of the working of the actual 

 law which is supposed to be capable of producing such an ad- 

 vance of grade ; but something approaching to it in effect has 

 been observed. Sex is fully ascertained to be a matter of 

 development. The ingenious Ruber first made us aware of an 

 instance, in a humble department of the animal world, of 

 arrangements being made by the animals themselves for ad- 

 justing the law of development to the production of a particular 



