EMBRYO OF MAMMIFERA. 51 



nificance, according to Haeckel, observable in trac- 

 ing the ontogenesis of man must be recognised in 

 the fact that the development of his body from the 

 very commencement takes place in the same manner 

 that the development of the body of other mammifera 

 does, and that all the peculiarities of individual de- 

 velopment which distinguish the mammifera generally 

 from other vertebrata are to be found also in man. 

 This I admit, but I cannot admit the validity of the 

 inference which Haeckel draws from it in support of 

 the doctrine of Evolution. 



The development of the embryo of certain mam- 

 miferous animals a rabbit or dog, for example has 

 been -well made out ; and in a few instances the 

 opportunity has presented itself of examining even 

 the human embryo, thrown off by miscarriage, at a 

 very early stage of its' development ; and enough 

 has been thereby ascertained to show that, in main 

 features, the early human embryo does not differ 

 much externally from the correspondingly early 

 embryo of other mammiferous animals. But not- 

 withstanding that .the ova of man and mammiferous 

 animals thus resemble each other, the ova of no two 

 kinds are exactly alike even in outward appearance ; 

 whilst potentially they differ from each other just as 

 the different kinds of animals do which spring from 

 them. Though the mechanism of the process of de- 

 velopment into the embryo be the same, the resulting 

 animal is different. By virtue of their own inherent 

 vital endowments and potentialities, the constituent 



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