INHERITANCE DUE TO CONTINUITY. 159 
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 
Jess 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 
surrounding it,—in the widest sense of the word from the 
