34: THE PLANT. 



plant itself become enlarged, and exert their influence 

 in proportion as the external conditions are favourable. 



The developement of the biennial plants cultivated 

 for their roots has three distinct periods ; in the first 

 period the leaves principally are formed ; in the second, 

 the roots, in which are stored the substances needed to 

 produce the flower and fruit during the third period. 



A series of experiments, made by Anderson, upon 

 turnips, affords a clear viewpf the several directions in 

 which the energy of a biennial plant tends at different 

 periods of its growth. (' Journal of Agriculture and 

 Transactions of the Highland Society,' No. 68, 69, 

 new series, 5.) 



These experiments were made to ascertain the total 

 produce of vegetable substances obtained from turnips 

 on one acre of ground. The turnips were gathered at 

 four different stages of growth ; the first on July 7, the 

 second, on August 11, the third, on September 1, and 

 the fourth, on October 5. The following table shows 

 the weight of leaves and roots in pounds, taken up at 

 the end of the respective stages, and calculated upon 

 one acre of ground. 



Weight of leaves. Weight of roots. 



I. Harvest after 32 days .... 219 pounds 7'2 pounds 



II. " 67 " . . . . 12,793 " 2,762 



III. " 87 " .... 19,200 " 14,400 " 



IV. " 122 " .... 11,208 " 36,792 



The relative quantities of leaves and roots show that 

 in the first half of the time of vegetation, sixty-seven 

 days, the organic labour in the turnip plant is princi- 

 pally directed to the production and developement of 

 the external organs. 



From the 7th July to the llth August, a period 

 of thirty-five days, we find the increase to be 12,574 

 pounds in the leaves, and 2,755 pounds in the roots, 

 which gives a daily increase of 



Leaves. Hoots. 



359 pounds. | 78 pounds. 



In this stage, accordingly, the production of leaves 

 prevailed over that of roots to this extent, that out of 



