GROWTH OF THE OAT-PLANT. 



37 



sphere and from the ground, or the absorptive power of 

 the plant, should alter and increase, by fits and starts, from 

 one day to another. We are led rather to assume that 

 'the oat-plant is subject in its developement to the same 

 law which we have observed in the case of the tiu'nip, and 

 that therefore, in the second half of the first stage of 

 growth, the activity of the leaves was principally directed 

 to the production of organisable matter, to be stored up 

 in the root for the shooting stage, and then supplied to 

 the overground organs of the plant. The heightened as- 

 similative or working power of the plant, consequent upon 

 the higher temperature and brighter sunshine of summer, 

 was attended by a proportionate increase in the supply of 

 food ; but the relative proportion of the soil constituents 

 remained much the same as in the turnip plant. 



If we compare the respective quantities of potash, phos- 

 phoric acid, and nitrogen, which the overground parts of 

 the oat-plant have received from the root and the soil, in 

 the several stages of growth, i. e. to the commencement of 

 flow^ering, thence to incipient ripening, and finally to ma- 

 turity, we find that 1,000 plants have received : — 



These proportions show that the daily increase of potash 

 in the overground parts of the oat-plant was pretty nearly 

 the same in the 21 days of the 3rd and 4th stages, as in 

 the 61 days of the 1st and 2nd. But for the phosphoric 

 acid and the nitrogen a very different result is obtained ; 

 we find that the quantity of these two ingredients whicJi 

 passed into the stalk, the ear, and the leaves, amounted 



