316 LIGHT REGULATES 



additional concentration up, even to that which 

 would burn the plants if dry, and boil them if 

 moist, could be obtained ; but then, as there is 

 no calculating when it shall be sunshine and when 

 cloudy, the transition from the artificially increased 

 sunbeams to the natural shadow of clouds would 

 be destructive. Thus the safe plan is to regulate 

 all the other matters by the natural light. 



Here, a little fact presents itself, which is not 

 wholly unworthy of notice. The first necessary 

 that man has to find, by skill and artificial means, 

 is food ; and light, the agent in vegetation over 

 which he has the smallest control, appears to 

 have less to do in preparing vegetables for food 

 than in preparing them for any other purpose. 

 Succulent, pulpy, and farinacious matter, the 

 kinds which are most nutritive, are best when 

 prepared out of the immediate reach of light. 

 When part of a potato is above the surface, the 

 light turns it green, and the taste is unpleasant. 

 Allow it to be formed and to grow altogether in 

 the light, and it is not edible, neither will it make 

 into starch. Its qualities approximate those of 

 a leaf or a stone. Celery, and the other plants 

 which are generally made use of in a blanched 

 state, are unfit for being eaten if the light has 

 free access to them ; and generally where mere 

 nutriment is the object, it is best attained in the 

 shade. 



Forest trees, of which the cotyledons rise above 

 the surface, and perform the functions of leaves, 

 are not so much deteriorated by the nursery mode 

 of sowing, as those of which the cotyledons re- 

 main below, but still they are all injured less or 

 more, so that no planted tree forms timber equal 



