96 GLEANINGS FROM NATURE. 



He has a pasture of 80 acres, and at present it takes 

 but two hours' mowing, twice or three times a year, 

 to rid it of the weed; whereas, just across the way is 

 a pasture where it holds undisputed sway from May 

 to August. 



This third farmer had studied botany and knew 

 that all plants have their food assimilated, that is, 

 fitted for their use, in their leaves. The crude food 

 materials, carbon-dioxide, water, and various nitrates 

 and other salts in a soluble form, are gathered from 

 the air and the earth by the leaves and roots; but in 

 the leaves alone these materials undergo certain chem- 

 ical changes and are transformed into starch and other 

 foods which can be used directly by the plant in its 

 growth. Any excess, not needed for growth, is stored 

 up in the seeds, buds, under-ground stems and roots, 

 for the purpose of furnishing the young plant or the 

 growing shoot sufficient nourishment, to live upon 

 while it is developing leaves which in time will gather 

 and assimilate a new supply of food. 



This farmer, knowing all these facts, reasoned that 

 if he cut his iron-weeds in May, again in June, and 

 still a third time in July, the perennial roots would 

 not be filled with nourishment at the end of the season, 

 as their extra supply would be needed to start new 

 shoots each time the old ones were destroyed. More- 

 over, the leaves would not have time sufficient to pro- 

 duce much excess of food to be stored up in the roots, 

 as all their powers would be taxed to furnish food for 

 the rapid growth necessary for the new shoot to arrive 

 at maturity before the season was over. He pro- 

 ceeded to act upon his conclusions with the above 



