174 SPECIES AND KINDS. [l-ESSON 28. 



and between the latter and the Scarlet Oak : these, we take for 

 granted, have not originated from one and the same stock, but from 

 three separate stocks. Nor do we deny it on account of every 

 difference ; for even the sheep of the same flock, and the plants 

 raised from peas of the same pod, may show differences, and such 

 differences occasionally get to be very striking. When they are 

 pretty well marked, we call them , 



Varieties. The White Oak, for example, presents two or three 

 varieties in the shape of the leaves, although they may be all alike 

 upon each particular tree. The question often arises, practically, 

 and it is ofleii hard to answer, whether the difference in a particular 

 case is that of a variety, or is specific. If the former, we may 

 commonly prove it to be so by finding such intermediate degrees 

 of difference in various individuals as to show that no clear line of 

 distinction can be drawn between them ; or else by observing the 

 variety to vary back again, if not in the same individual, yet in its 

 offspring. Our sorts of Apples, Pears, Potatoes, and the like, show 

 us that diflferences which are permanent in the individual, and con- 

 tinue unchanged through a long series of generations when propa- 

 gated by division (as by offsets, cuttings, grafts, bulbs, tubers, &c.), 

 are not likely to be reproduced by seed. Still they sometimes are 

 so : and such varieties are called 



Races. These are strongly marked varieties, capable of being 

 propagated by seed. Our different sorts of Wheat, Indian Corn, 

 Peas, Radishes, &c., are familiar examples : and the races of men 

 offer an analogous instance. 



502. It should be noted, that all varieties have a tendency to be 

 reproduced by seed, just as all the peculiarities of the parent tend to 

 be reproduced in the offspring. And by selecting those plants which 

 have developed or inherited any desirable peculiarity, keeping them 

 from mingling with their less promising brethren, and selecting again 

 the most promising plants raised from their seeds, we may in a few 

 generations render almost any variety transmissible by seed, so long 

 as we take good care of it. In fact, this is the way the cultivated or 

 domesticated races, so useful to man, have been fixed and preserved. 

 Eaces, in fact, can hardly, if at all, be said to exist independently of 

 man. But man does not really pt-oduce thert. Such peculiarities 

 — often surprising enough — now and then originate, we know not 

 how (the plant sports, as the gardeners say) ; they are only pre- 

 served, propagated, and generally further developed, by the culti- 



