INHERITANCE DUE TO CONTINUITY. 1 59 



These are the two fundamental qualities of animals and 

 plants of which the breeder must avail himself in order to 

 produce new forms. The theoretical principle of breeding 

 is, indeed, extremely simple, but in detail the practical appli- 

 cation of this simple principle is difficult and immensely 

 complicated. A thoughtful breeder, acting according to 

 a definite plan, must understand the art of correctly esti- 

 mating, in every case, the general interaction between the 

 two fundamental qualities of heirship and mutability. 



Now, if we examine the real nature of those two impor- 

 tant properties of life, we find that we can trace them, like 

 all physiological functions, to physical and chemical causes, 

 to the properties and the phenomena of motion of those 

 substances of which the bodies of animals and plants 

 consist. As we shall hereafter have to show in the more 

 accurate consideration of these two functions, the trans- 

 mission by Inheritance, if we express ourselves quite 

 generally, is essentially dependent upon the material con- 

 tinuity and partial identity of the matter in the producing 

 and produced organism, the parents and the child. In 

 every act of breeding a certain quantity of protoplasm or 

 albuminous matter is transferred from the parents to the 

 child, and along with it there is transferred the individually 

 'peculiar molecular motion. These molecular phenomena of 

 motion in the protoplasm, which call forth the phenomena 

 of life, and are their active and true cause, differ more or 

 less in all living individuals ; they are of infinite variety. 



Adaptation, or transmutation is, on the other hand, 

 essentially the consequence of material influences, which the 

 substance of the organism experiences from the material 

 suiTounding it, — in the widest sense of the word from the 



