40 THE PL.\NT. 



oat-plant were 2-45 times greater than that of the turnip, 

 the former would, under like circumstances, take up daily 

 2-45 times as much food as the latter, i.e. the oat-plant 

 would absorb in 50 days as much as the turnip in 122 

 days. Thus in equal times the power of two plants to 

 absorb food is in proportion to their absorbent root- 

 sm^face. 



The time of vegetation occupied by the turnip-plant 

 comprises, in the first year, 120 to 122 days, and termi- 

 nates at the end of July in the next year "with the produc- 

 tion of seed. If we take the whole time of vegetation of 

 the turnip-plant at 244 days, and suppose the time of 

 vegetation of the oat-plant extended from 93 or 95 to 

 244 days, we find that tliis would give sufficient time for 

 growing two oat crops, and advancing a third half way to 

 maturity ; and a careful investigation might perhaps reveal 

 that the quantity of sulphureous and nitrogenous consti- 

 tuents produced in the oat-plant is not less than that 

 obtained in turnip-plants from an equal area of ground. 



In the grains of the cereals the quantity of the sulphur- 

 eous and nitrogenous constituents is to that of the non- 

 nitrogenous (the quantity of the blood-making substances 

 to the amylum), as 1 : 4 or 5 ; in the roots of turnips, or 

 in the tubers of potatoes, as 1:8 or 10. In the latter, 

 therefore, the quantity of the non-nitrogenous constituents 

 is in proportion to the other constituents much greater. 



When at a certain temperature the organic process of 

 germination begins in a grain of wheat, the embryo first 

 sends down a number of rootlets, while the plumule rises 

 upward in the form of a short stem, with two or three 

 complete leaves. Simultaneously with the changes taking 

 place in the embryo, the constituents of the farinaceous 

 body (albumen) become fluid ; the amylum is converted 

 first into a substance resembling gum, then into sugar. 



