The Ottawa Naturalist. 



13 



the familiar substances, sugar, starch, fibre and a class of nitrogen- 

 containing bodies known as albuminoids or proteids. Of these the gluten 

 of wheat and other grains, forms a well known example. 



The sugar, starch, fibre and other non-nitrogenous organic con- 

 stituents are built up by the physiological functions of the plant from 

 the carbonic acid, which exists to the extent of 4 volumes in 10,000 

 volumes of the atmosphere. This absorption and assimilation takes 

 place by means of the plant's chorophyil (or green colouring matter) in 

 the presence of sunlight, oxygen by the same process being evolved. 

 The carbon (the fundamental element in organic bodies) of the album- 

 inoids is also derived from the same source. It will thus be seen that 

 by far the greater part of the dry mat'.er of all plants is derived directly 

 from the atmosphere. It may be pointed out in passing that in this 

 way the carbonic acid exhaled by animals is utilized, and thus the 

 approximate constancy in the proportions of the Atmospheric elements, 

 maintained. The production and consumption of carbonic acid and 

 oxygen thus effected, provides for the welfare of both plants and 

 animals. 



PLANT CONSTITUENTS. 



The 

 Organic 

 elements 



The 

 Inorganic 

 elements 



Until recent years, it was believed that all plants absorbed their 

 nitrogen from nitrogen-containing bodies (chiefly humus) in the soil, 

 and from this source only. It has now, however, been definitely 

 ascertained, as the result of many carefully conducted experiments in 

 Germany and England, that certain plants have the power of utilizing 

 the free nitrogen of the air, building it up within their tissues into 

 complex organic substances, as the albuminoids. These plants are 

 known as the Legumes, comprising the well known plants, pea, bean 



