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 Rheas,) 
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 t 
roots nor the stems cut into pieces and steeped in water, produce in 
it, any of the changes which the growing plants communicate. 
Euphorbiaceous Plants—The Euphorbia eyparisias 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. Baes alcohol dis- 
solves the residuum and deposits by evaporation, a granular, gummo- 
os yellowish white, very acrid substance, leaving a strong after 
pa loa Plants.—The only plant of this family which I Tava 
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 
plants whose roots secrete little or nothing of a. decided char- 
acter. This however is the result of only a angie 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 theit 
vegetation. 2d, That the nature of those substances varies accord- 
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