336 QUAKTERLY JOURNAL. 



reestablishing its original compositionj and consequently, by r&» 

 turning to it the principles which we had reaped and removed inii 

 the plants. 



Two plants may be cultivated side by side, or one after theil 

 other, if they require unequal quantities of the same principles in 

 unequal times ; they will not be injured, and their vegetation will 

 be beautiful, notwithstanding their proximity, if they require for 

 their development different principles of the soil. 



The investigations of M. de Saussure and many other natural- 

 ists, have shown that the seeds of the Viciafaba of the Phaseoltis 

 vulgaris, of peas and garden cress {lepidium sativum,) germinate 

 and are developed to a certain degree in wet sand, and in horse- 

 hair kept in a state of humidity ; but when the mineral substances 

 contained in the seed are no longer sufficient for the further de- 

 velopment of these plants, they begin to droop ; they sometimes 

 flower, but they never produce seeds. 



Wiegraann and Polstorff made plants of different kinds vege- 

 tate in white sand boiled with aqua regia and freed 'from acid bj 

 careful washing ;* barley and oats sown in this sand, and suffi- 

 ciently moistened with water free from ammonia, reached th( 

 height of 0m487 ; they flowered, but produced no seeds, am 

 perished after flowering. The Vicia sativa attained the height o 

 0m27, flowered, and produced husks ; but they contained no seed 



Tobacco sowed in this land presented a perfectly normal de 

 velopment ; but from June to October, the little plants attaine( 

 only the height of Oml4 : they had only four leaves withou 

 stalks. 



The examination of the ash of these plants, as well as the an 

 alysis of the seeds, showed that this land, sterile as it was by it 

 self, and poor as it was in potassa and soluble principles, never 

 theless yielded to them a certain quantity of these substance 

 which had served for the development of the stalks and leaves 

 But these plants could not bear seed, because evidently there wa 

 a complete absence of the substances necessary for the formatioi 

 of the principles of the seeds. 



In the ash of most of the plants grown in this sand, might th 

 presence of phosphoric acid be demonstrated ; but it correspondei 

 only to the quantity of that acid introduced into the soil by th^ 

 seed. In the ash of tobacco, whose seeds are, as is known, si 

 small that the phosphoric acid which they contain eludes analysis 

 it was impossible to detect any trace of it. 



• This sand contained in 1,000 parts : 



Silica 979.00 



Potassa 3.20 



Alumina 8.76 



Peroxide of iron 3.15 



Lime 4.84 



Magnesia 0.09 



