304 IMPREGNATION OF THE SEED. CHAF. VII. 



reasons the theory of the ovarist seems to me to be 

 much more consonant to truth than that of the 

 animalculist. 



SUBSECTION in. 



Theory of the Epigenisist. But the difficulties 

 inseparable from both theories, together with the 

 phenomenon of hybrid productions, have given 

 rise also to a third ; this is the theory of the epige- 

 nisists, who maintain that the embryo pre-exists 

 neither in the ovary nor pollen, but is generated by 

 the union of the fecundating principles of the male 

 and female organs ; the former being the fluid is- 

 suing from the pollen when it explodes ; and the 

 latter, the fluid that exudes from the surface of the 

 Asde- stigma when mature. As applicable to the case of 

 pl ants ? tn is theory has been stoutly defended by 

 Koelreuter, who adduces in support of it a variety 

 of experiments instituted with a view to ascertain 

 the fact by means of impregnating the ovary of 

 one species with pollen taken from another, in 

 which cases the plant obtained from the seed uni- 

 formly exhibited a combination of the characters 

 of both species. The following is a most promi- 

 nent example, being the result of his experiments 

 on Nicotiana rusiica and paniculata ; the former 

 having egg-shaped leaves, with a short and yellow 

 corolla approaching to green ; and the latter having 

 roundish or cordate leaves, with a green corolla 

 approaching to yellow, and a stem longer by onfc 



