56 



On the Inorganic Constituents of Plants, 



plant continues to increase far more rapidly than the inorganic 

 matters do : hence the real proportion of the latter appears to de- 

 crease. In the experiment however, on Savoys, first described, it 

 would seem that the young leaves contained in reality less earthy 

 matter, than the older leaves ; and that in them the proportion of 

 inorganic to organic matter, was smaller than in the older leaves. 

 On comparison it was found that a very marked difference existed 

 in the composition of these inorganic matters ; a proximate analysis 

 gave 



Siliceous matter . . . 500 in 10000. 1037 in 10000. 



The young leaves of the Savoy are so completely protected from 

 air and light that they can hardly be well compared with the 

 young leaves of ordinary plants, which as soon as they emerge from 

 the bud are to a greater or less degree exposed to the light. In 

 order to ascertain what influence light has on the absorption of 

 inorganic matters, a number of hyacinths were grown, some in 

 light and some in darkness ; the following were the results. The 

 bulbs selected were as nearly as possible similar in size and weight; 

 half were planted in dark and half in light, some in water only, 

 others in rich artificial soil, and the rest in sand. Four of the 

 roots being dried thoroughly and burnt, their composition w as found 

 to be very nearly uniform ; they consisted of 6435 water, 3442 

 organic matter, and 123 parts of inorganic matter. After growing 

 and flowering the plants were examined ; in some instances those 

 grown in the dark contained the greatest proportion of inorganic 

 matters, whilst in other cases they were found to contain less, than 

 those grown in light. The average of the whole series was 



Plants grown in water; light . 9231 769 



