44 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



It reposes on the important law of which Geoff roy- 

 Saint-Hilaire, Serres, and Miiller had already ob- 

 tained glimpses, and which was appealed to over 

 and over again by Darwin which law may be 

 formulated in the following terms : the embryogenical 

 development of an actual living being is a brief abstract 

 of the phases through which has passed the palceonto- 

 logical development of the group to which the species 

 under examination belongs. In other words, adopt- 

 ing the language of Haeckel, " The ontogeny is a 

 repetition, a brief and rapid recapitulation of the 

 phytogeny conformably to the laws of heredity and 

 adaptation." 



This law of the parallelism of phylogeny and of 

 ontogeny, very important from the philosophical 

 point of view, and capable of casting a general light 

 on the researches into the evolution of animals, 

 requires, nevertheless, to be handled with extreme 

 prudence. It could in no case allow us to dispense 

 with the control furnished by real evolution, that is 

 to say, by the knowledge of the palaeontological 

 documentary evidence. Its too strict and exclusive 

 application could not fail to lead Haeckel into 

 grave errors. 



Bolder than Darwin, the learned German zoologist 

 did not hesitate to set about reconstituting by 

 the embryogenic method, the general pedigree of 

 organized beings, animal and vegetable, commenc- 

 ing with the appearance of life on the globe down 

 to the present day. At the head of his system 

 stands a primary and inevitable hypothesis, that 

 of the apparition of the first germ of life by means 

 of spontaneous generation. 



