314 EXPEBIMENTS WITH PLANTS 



seed begins to ripen the plant stops growing and 

 the stored food moves toward the seeds, where it 

 becomes concentrated, leaving the stalks empty of 

 nntriment so that they cannot be used as food for cat- 

 tle. The withdrawal of food from the stalk goes on 

 after the stalk is cut, consequently the best time for 

 cutting grain is just before it is fully ripe ; it can then 

 be transported without loss of seeds by shaking, and 

 will absorb nutriment from the stalk and ripen as well 

 as if left uncut (this does not apply when the grain is 

 "headed," i. e., when the head is removed from the 

 stalk by a special machine known as a "header"). For 

 a forage crop, like hay, cut after the seeds are formed 

 but before they are ripe. 



A great number of plants (annuals, biennials, also 

 the Century Plant, etc.) resemble the Grains in giving 

 up all their store of food to the seeds, and dying after 

 the seed is ripe. Is the food transformed on reaching the 

 fruit? The seeds of the Rape contain, while develop- 

 ing, much starch, which can be traced from the leaves 

 directly to them; but, when mature, this is all changed 

 into proteids and fats. Examine any available plants 

 which have oily seeds or fruits, to see if the same is 

 true of them. 



In fruits and seeds which contain large quantities of 

 sugar, is there any indication that starch accumulates 

 and is subsequently transformed into sugar? 



Along with the production of sugar there is, in many 



