70 SOURCE AND ASSIMILATION 



nitrogen to vegetable albumen, and gluten., to fruits 

 and seeds ? 



This question is susceptible of a very simple 

 solution. 



Plants, as we know, grow perfectly well in pure 

 charcoal, if supplied at the same time with rain- 

 water. Rain-water can contain nitrogen only in two 

 forms, either as dissolved atmospheric air, or as am- 

 monia. Now, the nitrogen of the air cannot be made 

 to enter into combination with any element except 

 oxygen, even by employment of the most powerful 

 chemical means. We have not the slightest reason 

 for believing that the nitrogen of the atmosphere 

 takes part in the processes of assimilation of plants 

 and animals ; on the contrary, we know that many 

 plants emit the nitrogen, which is absorbed by their 

 roots, either in the gaseous form, or in solution in 

 water. But there are on the other hand numerous 

 facts, showing, that the formation in plants of 

 substances containing nitrogen, such as gluten, 

 takes place in proportion to the quantity of this 

 element which is conveyed to their roots in the 

 staje of ammonia, derived from the putrefaction of 

 animal matter. 



Ammonia, too, is capable of undergoing such a 

 multitude of transformations, when in contact with 

 other bodies, that in this respect it is not inferior to 

 water, which possesses the same property in an emi- 

 nent degree. It possesses properties which we do 

 not find in any other compound of nitrogen ; when 



