52 



On the Inorganic Constituents of Plants, 



considered as any evidence that the Nitrate does not supply Nitro- 

 gen to the plant. It might in the same way be argued, that Ammo- 

 nia does not supply nitrogen to plants, because it is very constantly 

 found in them. With regard to the disappearance of the Nitric Acid 

 at a certain period of the life of the plant, it is desirable to have 

 experimental evidence ; I have found in several cases that the pro- 

 portion of Nitric Acid in plants was great when they were young 

 and gradually diminished as they grew older. I have already 

 adverted to the curious fact that when plants were manured with 

 Nitrates they grew very vigorously, but were not found on exami- 

 nation to contain any Nitric Acid ; in the experiments on potatoes 

 just described, it appears, that those manured with Salt Cake and 

 Nitrate of Soda (No. 13), contained no Nitric acid, whilst those 

 manured with Salt Cake alone (No. 5), did contain Nitrates. In the 

 course of an extensive series of experiments on plants, presently to 

 be described, Nitric acid was found in the following : — 



Victoria Brocoli — stems. 8 ' 



Spinach, Flanders, Lettuce-leaved and Summer— 



As considerable facilities are afforded for experiments on the 

 absorption of earthy matters, by Parasitical plants and Epiphytes 

 several experiments were made with these curious plants. Setting 

 out with the known fact, that all plants contain certain inorganic 

 matters, it became interesting to enquire whence those plants 

 which grow on or derive their nourishment from other plants, 

 obtain their earthy matters. It follows, that if parasites derive the 

 earthy matters necessary to their growth, from the plants on which 



