28 Heredity. 



So far as it is a statement of facts, it cannot be called 

 an hypothesis, for it simply affirms that the egg is opti- 

 cally an ordinary unspecialized cell; that it gives rise, 

 during the process of segmentation, in a manner which is 

 identical with ordinary growth by cell division, to anum-, 

 ber of cells which gradually become specialized for cer- 

 tain functions, and are set apart as the foundations of the 

 various organs of the body; that the repetition of this 

 process gives rise, at last, to the perfect body of the 

 mature animal; that the reproductive elements which are 

 to give rise to the next generation, originate, like all the 

 cells of the body, by cell division during the process of 

 development, and that they are simply cells specialized for 

 the reproductive function as other cells are specialized for 

 other functions. Every one who has the slightest ac- 

 quaintance with modern biology will accept this state- 

 ment, not ^s an hypothesis, but as an observed fact, and 

 will agree tha^between this and the old evolution hy- 

 pothesis there c\n be but one choice. 



The old hypothesis of evolution, however, claimed to 

 be something more than a statement o^fact, for the 

 presence of the germ within the egg accounted for the 

 wonderful properties of the egg itself. 



We are at once compelled to ask, then, how, on the 

 hypothesis of epigenesis, has the egg acquired these prop- 

 erties ? If it is simply an unspecialized cell; if, as Ge- 

 genbauer states, "the egg is nothing more nor less than 

 a cell; the egg-cell does not differ from other cells in 

 any essential points" (Comp. Anat., Bell's Trans., p. 18), 

 how can the egg of a horse develop into a horse, while 

 another cell, which " does not differ from it in any essen- 

 tial points," develops into a bee or an alligator or an 

 oyster ? 



Nothing in nature is more marvellous than the devel- 



