CHAPTER IV. — SPECIAL PHYSIOLOGY OF REPRODUCTION. 783 



ineffective for generations, are, as it were, set free in consequence 

 of some fresh crossing or of some important change in the con- 

 ditions of life, so that the latent ancestral characters now reveal 

 ithemselves. It is scarcely possible to offer any satisfactory ex- 

 planation of variation due to other causes, but there is one point 

 which, in conclusion, demands special consideration ; that is, 

 whether or not variations which are the result of the influence 

 of the external conditions, can be transmitted to the offspring. 

 I There is no doubt that they can be transmitted by means of 

 (Vegetative propagation. But the real question is as to whether 

 or not they can be transmitted through the sexual process; as 

 to whether or not the ids in the gamete of an individual can 

 transmit not only the ancestral characters, but also characters 

 which presented themselves apparently for the first time in the 

 individual itself. The wgight of opinion is at present in favour of 

 the view that such acquired characters cannot be so transmitted ; 

 but in the face of the fact that some variations apparently of this 

 nature (e.g. doubling of flowers, variegation of leaves) are often 

 transmitted in this way, it cannot be conceded that this view is 

 conclusively established. 



V. S. B. 3 E 



