Delage 265 



each change which their particular substance experiences 

 in the egg. 



In the third place, this would at all events suffice 

 only for the explanation of inheritance of those char- 

 acters which develop in the parent organism under the 

 influence of definite chemical actions, distributed through- 

 out the whole body, and acting only upon those particles 

 or cells of the body which have a certain chemical com- 

 position. But what explanation could that give of true 

 morphological inheritance and so of the inheritability 

 of the growth or of the atrophy of an organ resulting 

 from too much or too little use? of the inheritability 

 of the spongy structure of bone, of the conformation of 

 the eye, and of all functional adaptations in general? 



Yet Delage gives the following explanation of the 

 inheritance of the atrophy of unused organs. 



"That only is determined in the egg, which is not 

 determined by functional excitation, but the amount 

 determined by the latter is enormous." The absolute 

 uselessness of slight reductions of the atrophied femur 

 of the whale and the consequent inefficacy, in this respect, 

 of natural selection, and on the other hand, the impos- 

 sibility of understanding how the slight reduction in 

 volume which the femur undergoes during the life of 

 the individual can extend its influence to the egg, and 

 determine in that the modification necessary for the 

 reproduction, in the following generations, of this new 

 reduction in volume, "forces us to admit," continues the 

 author, "that neither in consequence of a fortuitous 

 variation fixed by natural selection, nor in consequence 

 of an acquired and inherited modification does the egg 

 of the existing whale differ in so far as the femur is 

 concerned, from the eggs which produced the whales 



