666 RECORD OF CURRENT RESEARCHES RELATING TO 



The following day at 12 . 30 this experiment was repeated with a 

 like result, the leaves, the terminal leaflet of which was struck, going 

 to sleep in the space of four and a half minutes. It took, however, 

 tioo to three hours' sunlight to restore the lateral leaflets to their former 

 horizontal position. 



This falling down one after the other of the leaflets, com- 

 mencing from the extremity of the leaf, is exactly similar to what is 

 observed in the sensitive plant, in which, as the author showed in 

 1876,* there is simply the development in the highest degree of a 

 phenomenon which is traceable throughout the whole vegetable 

 kingdom. 



The application of a strong heat to the terminal leaflet, which acts 

 immediately on the sensitive plant, produced no eifect on the lateral 

 leaflets of the Acacia, even when the terminal leaflet was crisped and 

 burnt by a small flame. This seems to the author to demonstrate 

 that the sap is much less mobile in the tissue of the one plant than 

 in that of the other. 



Copper in Plants.f — In a recent memoir,| M. Dieulafait showed 

 that copper exists in a state of complete diffusion in all the rocks 

 of the primordial formation, and in those resulting directly from 

 their destruction. Among other consequences of this, all plants 

 which grow on such rocks should contain copper in sensible pro- 

 portion. 



M. Dieulafait has tested this view, and the following are the 

 results of his investigations: — 



Copper exists in all plants which grow on rocks of the. prim or dial 

 formation. Its proportion is sufficient for it to be recognized v/ith 

 certainty, even with the ammonia-reaction, by using only 1 gramme 

 of ash. 



Each of the one hundred and twenty-eight specimens of white 

 oak of marly strata showed the presence of copper with 1 gramme of 

 ash, though, in general, the proportion of the metal was less than that 

 in plants of primordial strata. 



All the specimens obtained in dolomitic horizons furnished 

 copper distinctly recognizable in 1 gramme of ash ; but there were 

 great variations according to the specimens. 



The plants which live on comparatively pure limestones did not 

 furnish any traces of copper under the conditions of the three fore- 

 going groups. To be able to recognize it with certainty, it was 

 necessary sometimes to use as much as 100 grammes of ash. 



Does copper exist normally in organs of animals and in those of 

 man ? The facts brought out in the present and previous memoir 

 naturally led up to this question, which is shown to be less simple 

 and absolute than has been believed hitherto. M. Dieulafait hopes 

 shortly to communicate facts as to animals and man living on the 

 primordial formation. 



* ' Familiar Letters on some Mysteries of Nature,' &e., p. 139. 



t ' Comptes Rendus,' xc. (1880) p. 703. 



J ' Annales de Chimie et de Physique,' 5th ser., xviii. 



