142 Vegetable Physiology. 



Gramineous Plants. — Wheat rye and barley were examined. 

 They do not grow well in rain water, probably from the notable quan- 

 tity of mineral substances, especially silex, which they contain, and 

 which they cannot derive from pure water. The water in which 

 they have vegetated is clear, transparent, without color, smell, or taste. 

 It contains some salts, alkaline and earthy muriates and carbonates, 

 and only a very small portion of gummy matter. He thinks these plants 

 reject scarcely any thing but the saline matters foreign to vegetation. 



Chicoraceous Plants. — The Chondrilla muralis and the Sonchus 

 oleraceus live very well in rain water. The latter acquires a clear 

 yellow color, a strong smell, and a bitter taste. Treated with tests, and 

 concentrated by evaporation it is found to contain tannin, a brown 

 gummo-extractive substance, and some salts. 



Papaveraceous Plants. — Plants of field poppy {Papaver Rhceas,) 

 will not live in rain water ; they speedily fade. The white poppy 

 (papaver somniferum) lives very well. The roots produce a yellow 

 color, a vinous odor, a bitter taste, and the brownish residuum might 

 be taken for opium. This plant is one of those which neither the 

 roots nor the stems cut into pieces and steeped in water, produce in 

 it, any of the changes which the growing plants communicate. 



Euphorbiaceous PlaMs. — The Euphorbia cyparisias and E. pep- 

 lus, are the plants from whose roots Brugmans observed the exuda- 

 tion of drops during the night. The author has not been able to ver- 

 ify this fact by direct observation. The plants vegetate well in rain 

 water, giving a very strong and persisting odor. Boiling alcohol dis- 

 solves the residuum and deposits by evaporation, a granular, gummo- 

 resinous, yellowish white, very acrid substance, leaving a strong after 

 taste. 



Solanaceous Plants. — The only plant of this family which I have 

 tried in water is the potato. It lives well in rain water and puts forth 

 its leaves. The water is scarcely colored, leaves little residuum, 

 gives but little taste, which induces the belief this is one of the 

 plants whose roots secrete little or nothing of a decided char- 

 acter. This however is the result of only a single hasty experiment 

 made upon a plant at an early stage of its development. 



The inferences which the author deduces from his experiments 

 (acknowledging however that more extended trials on a greater num- 

 ber of families and individuals are desirable,) are, 1st, that the greater 

 number of vegetables exude by their roots substances unfit for their 

 vegetation. 2d, That the nature of those substances varies accord- 



