240 THE INDUCTIONS OF BIOLOGY. 



have been produced divergent modifications of the same 

 species ; and abundant proof exists that the members of any 

 one sub-species, habitually transmit their distinctive pecu- 

 liarities to their descendants. Agriculturists and 

 gardeners can furnish unquestionable illustrations. Several 

 varieties of wheat are known ; of which each reproduces 

 itself. Since its introduction into England, there have been 

 formed from the potato, a number of sub-species: some of them 

 differing greatly in their forms, sizes, qualities, and periods- 

 of ripening. Of peas, also, the like may be said. And the 

 case of the cabbage-tribe, is often cited as showing the per- 

 manent establishment of races that have diverged widely 

 from a common stock. Among fruits and flowers, the multi- 

 plication of kinds, and the continuance of eacji kind with 

 certainty by agamogenesis, and to some extent by gamo- 

 genesis, might be exemplified without end. From all 

 sides evidence may be gathered showing a like persistence of 

 varieties in each species of animal. We have our distinct 

 breeds of sheep, our distinct breeds of cattle, our distinct 

 breeds of horses : each breed maintaining its characteristics. 

 The several sorts of dogs, which, if we accept the physiolo 

 gical test, we must consider as all of one species, show us in 

 a marked manner the hereditary transmission of small difi'er- 

 ences — each sort, when kept pure, reproducing itself not 

 only in size, form, colour, and quality of hair, but also in 

 disposition and speciality of intelligence. Rabbits, too, have 

 their permanently- established races. And in the Isle of Man, 

 we have a tail-less kind of cat. Even in the absence 

 of other evidence, that which ethnology furnishes would 

 suffice. Grant them to be derived from one stock, and the 

 varieties of man yield proof upon proof that non-specific 

 traits of structure are bequeathed from generation to gener- 

 ation. Or grant only that there is evidence of their deriva- 

 tion from several stocks, and we still have, between races de- 

 scended from a common stock, distinctions which prove the 

 inheritance of minor peculiarities. Besides seeing that 



