TRANSMUTABLE. 225 



3rd. "Embryos of different species within the 

 same class, generally, but not universally resemble 

 each other." A great deal too much has been 

 made out of this fact by theorists. M. Serres 

 has founded upon it the following generalization : 

 "Human organo-genesis is a transitory com- 

 parative anatomy, as, in its turn, comparative 

 anatomy is a fixed and permanent state of the 

 organo-genesis of man." "But," as remarks Pro- 

 fessor Bennett, (Outlines of Physiology, p. 180,) 

 "that the human embryo ever resembles a worm, 

 a mollusc, reptile, fish, or bird, can, on careful 

 examination, nowhere be recognised. It is true 

 that at one time all ova resemble each other; 

 but it is equally certain, that from the first 

 moment of their formation, they are impressed 

 with a power of developing themselves only in 

 one direction, so that the ovum of a reptile, 

 fish, or bird, will always be developed into 

 similar animals, and by no concurrence of cir- 

 cumstances, will ever be transformed into different 

 ones." 



This obvious truth, speaking at once to the 

 conviction, ought to put an end to all the theories 

 which have been raised, upon the simple fact of 

 the early similarity of vertebrate embryos. 



4th. "The structure of the embryo is not 

 closely related to its condition of existence, ex- 

 cept when the embryo becomes at any period 

 of life active, and has to provide for itself." 

 Why should the structure of a transitional or- 

 ganism be related to that with which it is not 



