S20 M. Macaire on Vegetable Physiology. 



white poppy (Papaver somniferum) lives very well. The roots 

 produce a yellow colour, a vinous odour, 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. 



Euphorhiaceous Plants. — The Euphorbia cyparisias and E. 

 peplus^ are the plants from whose roots Brugmans observed 

 the exudation of drops during the night. The author has not 

 been able to verify this fact by direct observation. The plants 

 vegetate well in rain-water, giving a very strong and persisting 

 odour. Boiling alcohol dissolves 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 water, and 

 puts forth its leaves. The water is scarcely coloured, 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 character. This, however, is the result of only a 

 simple 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 

 number 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 these sub- 

 stances varies according to the families of plants which produce 

 them. 3d, That some being acrid and resinous, may be inju- 

 rious, and others being mild and gummy, may assist in the nou- 

 rishment of other plants. 4th, That these facts tend to confirm 

 the theory of rotation due to M. de CandoUe. 



