Vegetable Physiology. 141 



Similar trials were made with a weak solution of marine salt, and 

 with a like result. Learning from M. De Candolle that marine plants 

 when transported in a healthy situation, frequently grow well at a 

 distance from the sea, and that in such cases the soil in which they 

 grow contains more salt than the surrounding soil, the author endeav- 

 ored to imitate nature by taking a few common plants, placing their 

 roots in rain water, and wetting their leaves with a solution of ma- 

 rine salt. None of the salt was discoverable in the water, and it 

 may therefore be inferred either that solutions of salt cannot imitate 

 the delicate process of nature, or perhaps more probably that soda 

 plants alone have the power of absorbing by their leaves, marine 

 salt and rejecting a portion of it by their roots. 



There can be no doubt then that plants have the power of reject- 

 ing by their roots, soluble salts which are injurious to vegetation. The 

 author gives a fewjnteresting details of experiments on some partic- 

 ular families of plants. 



Leguminous Plants. — The only plants which he tried of this fam- 

 ily were peas and beans. They live and grow well in pure water. 

 After sometime, the liquid, being examined, has no sensible taste, its 

 smell is faintly herbaceous. It is quite clear and almost colorless in 

 the case of kidney beans, (haricots,) more yellow in peas and com- 

 mon beans, (feves.) The fluid when examined by chemical tests, 

 evaporation, &,c. is found to contain a matter very analogous to gum 

 and a little carbonate of lime. 



It was found that when the water in which these plants had lived 

 was pretty well charged with this excrementitious matter, fresh plants 

 of the same species soon withered in it and did not live well. To 

 ascertain whether this was for want of carbonic acid in the fluid, 

 (which plants derive from the earth as well as from the air,) or from 

 the presence of the excreted matter, which they repudiated, the au- 

 thor put into the fluid, some plants of another family, and especially 

 wheat. This lived well,- the yellow color of the fluid became less 

 intense, ^the residuum less considerable, and it was evident that the 

 new plant absorbed a portion of the matter discharged by the first. 

 It was a kind of rotation experiment performed in a bottle, and the 

 result tends to confirm the theory of De Candolle. It is not impos- 

 sible that by experiments of this kind, results may be obtained of prac- 

 tical importance to agriculture. The author would infer that wheat 

 may follow with great advantage a crop of beans. 



