FACT AND THEORY 247 



then, and only then, could we fully realize 

 the wonders which environment, blending with 

 that common heredity within the plant, has 

 wrought. 



We should see, among the seventy-five 

 brothers and sisters of that family, if they were 

 spread before us, the poisonous bittersweet, and 

 the humble but indispensable potato; the egg 

 plant and the Jerusalem cherry; the horse 

 nettle and the jimson weed; the tobacco plant 

 and the beautiful petimia; and the tomato 

 itself. 



We should see seventy-five plants with orig- 

 inal structural similarities, yet differing, in every 

 other way, as night differs from day; and we 

 should be able to trace, if we observed closely 

 enough, the points at which, in the history of this 

 family, new environment, oft repeated, has 

 hardened into heredity, subject to the call of 

 still new environment, which has not been lack- 

 ing to bring it out ; we should be able to trace, by 

 easy stages, why one branch ran to the poisonous 

 bittersweet, another to the potato with its food 

 product below the ground, another to the tomato 

 with its tempting fruit displayed on the vines 

 above; another to tobacco, valued for its chemi- 

 cal content — and so on throughout all of the 

 variations. 



