i6o VESTIGES OF THE 



during the ages whicli preceded its commencement, as 

 we do not know what may happen in ages yet in the 

 distant future. All, therefore, that we can properly 

 infer from the apparently invariable production of like 

 by like is, that such is the ordinary procedure of nature 

 in the time immediately passing before our eyes. Mr. 

 Babbage's illustration powerfully suggests that this 

 ordinary procedure may be subordinate to a higher law 

 which only iwrmits it for a time, and in proper season 

 interrupts and changes it. We shall soon see some 

 philosophical evidence for this very conclusion. 



It has been seen that, in the reproduction of the 

 higher animals, the new being passes through stages in 

 which it is successively fish-like and reptile-like. But 

 the resemblance is not to the adult fish or the adult 

 I'eptile, but to the fish and reptile at a certain point in 

 their ftetal progress ; this holds true with regard to the 

 vascular, nervous, and other systems alike. It seems as 

 if gestation consisted of two distinct and independent 

 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. This may be illustrated by a 

 simple diagram. The fcetus of all the four classes may 

 be supposed to advance in an identical condition to the 

 point A. The fish there diverges and passes along a 

 line apart, and peculiar to itself, to its mature state at 

 F. The reptile, bird, and mammal, go on together to 

 C, where the reptile diverges in like manner, and 

 advances by itself to R. The bird diverges at D, and 

 goes on to B. The mammal then goes forward in a 

 straight line to the higliest point of organisation at M. 



