44 THE PLANT. 



were grown in free atmospheric air, with the exclusion, 

 however, of dew and rain, 4*995 grammes of seeds 

 (hipines, beans, oats, wheat, and cresses) gave 18-73 

 grammes of dried plants. The seeds contained 0-2307 

 gramme of nitrogen ; the plants and soil, 0-2499 

 gramme. In the first seizes of experiments, all elements 

 of food were supphed to the plants, except nitrogen ; 

 the chief conditions required to form unazotised matter 

 were given, but those required to form azotised matter 

 were altogether excluded. 



The growth of a wheat plant in pure water and 

 atmospheric air is unattended with any increase of 

 weight. The normal seed-corn contains a certain 

 quantity of potash, magnesia, and hme, which are 

 required internally for the organic formative process ; 

 but it has no excess of these mineral substances that 

 could serve to effect the chemical process of a new pro- 

 duction of protoplasm. Wliere the mineral substances 

 are excluded, the organs will absorb water, but neither 

 carbonic acid nor ammonia; at all events, these two 

 latter substances, even though they be introduced into 

 the plant by means of the water, exert no influence upon 

 the internal process ; they suffer no decomposition, and 

 no vegetable matter is formed from their elements. 



In Boussingault's experiments, the action of the mineral 

 substances supphed is unmistakable. The weight of the 

 plants produced was nearly 3^ times greater than that of 

 the seeds sown : but the quantity of nitrogenous matter 

 was the same as in the seeds. Hence we have a clear 

 production of non-nitrogenous substance 2^ times more 

 than the original weight of the seeds. A simple calcula- 

 tion shows that the nitrogen in the seed has, under these 

 circumstances, caused the generation of 56 times its own 

 weight of unazotised matter ; or, what comes to the same 



