CROSSING AND CLOSE-INTERBREEDING. 233 



gard the significance of the important circumstance, 

 that the effects of the same degree of close-interbreed- 

 ing, vary widely, not only with individuals of different 

 species, but also with individuals of the same species, 

 and even of the same variety, and of the same breed, 

 both in the quantity of the evil, and in the period of 

 its recurrence. It is a consideration, of these circum- 

 stances, which moves many, even of the unlearned, to 

 scorn such an unphilosophical mode of induction (or 

 deduction, for it is hard to tell what it is), as Darwin 

 essays, when he postulates, or deduces, "a great law 

 of nature !" It would afford inexhaustible amusement, 

 to know what Darwin's major premise is, if his "great 

 law of nature" be a conclusion. It must be, in the 

 similitude of this: Phenomena, which are scientifically 

 inexplicable, are due to a "great law of nature;" the 

 phenomena of close-interbreeding, are scientifically 

 inexplicable; Ergo: the phenomena of close-inter- 

 breeding are due to "a great law of nature." If his 

 law be an induction: the mere intimation, to such 

 effect, should suffice to start Bacon from his grave, to 

 deplore the time, the event shows that he wasted, in 

 warning his disciples against the error of incomplete 

 induction. 



Breeders see, that, with such variations in the quan- 

 tity of effect, attendant upon close-interbreeding, the 

 process itself cannot be the cause, but must be the 

 occasion only. What the cause is, they are at a_ loss 

 to say. But, they can well see, that in-and-in breeding 

 is not the cause. 



A scientist, however, who may, — as Darwin has 



