292 THE LURE OF THE LAND 



INFLUENCE OF HEEEDITY. 



Science has shown that every species, and in fact 

 every variety, has an inherent power of variability. It 

 thus happens that the individuals of the same species or 

 race, while they have a close resemblance to one an- 

 other, are not exactly alike. Even the offspring of the 

 same parents, when subjected to the same conditions of 

 existence, as in the case of twins or polygenesis, are 

 easily distinguished from each other. This variation 

 from the type may be greater or less ; usually it is very 

 slight. Sometimes it is so great that it is called a 

 monstrosity. By crossing different species, to produce 

 hybrids, as in the case of mules and hinnies, a progeny 

 is produced in which the variation from the parent 

 forms is more marked. Hybrids often seem to possess 

 characters which are almost a mean of those possessed 

 by their parents, while often, also, by a certain prepo- 

 tency of generative force in one or the other of the pro- 

 genitors, the hybrid is attracted to one or the other of 

 the species from which it is produced. But this varia- 

 bility in animals would prove of little use to man were 

 it not for another principle, the law of heredity, which 

 science has also discovered and formulated. While it 

 is true that the offspring varies more or less from the 

 parent, it is equally true and equally as important that 

 there is also a greater or less resemblance between them. 

 From this it happens that there is always a tendency 

 for the parent to transmit to the offspring those pe- 

 culiarities which are its distinguishing marks. Let us 

 combine now with the two foregoing principles, viz., 

 variability and heredity, that of selection, and we have 

 the basis of the improvements of breeds, upon which 

 every scientific farmer acts. Science, in the last few 



