37^ 



Chemical Composition of Plants. 



of the Bureau of Chemistry, on the influence of environment on 

 the chemical composition of plants. 



The word environment is used to include the soil in which the 

 plant grows, the fertilizers which are added thereto, the character 

 of the cultivation to which the crop is subjected, and the climatic 

 influences during the year of growth. The study of the com- 

 position of cereals was begun as early as 1882 by Mr. Clifford 

 Richardson, who not only endeavoured to collate the analyses 

 made in other laboratories than those of the Division of Chemis- 

 try, but, on finding the results thus obtained unsatisfactory, 

 arranged that Professor Blount should analyse the products of 

 similar seeds grown in various parts of the United States. 



The results of these investigations show that variations in 

 the quality of the grain may be attributed to three principal 

 sources. 



(1) The inherent nature of the various species of wheat. 

 Very little information is given on this point, but it appears that 

 one class of wheat known as the Washington Glass variety gave 

 on analysis only 1 r86 per cent, of albuminoids, which even the 

 •soils of Colorado failed to improve. This wheat therefore shows 

 a certain deficiency in powers of assimilating nitrogen, and it 

 is generally admitted that the value of wheat for milling and 

 bread-making purposes depends more largely on its nitrogenous 

 contents than upon any other. It is true that starch is the most 

 abundant constituent of wheat and offers the largest amount of 

 nutritive food ; but the protein, representing the principal part 

 of the nitrogenous bodies, is the substance which gives the wheat 

 its characteristic properties for bread-making, because in the 

 protein are found those agglutinating constituents, together 

 known as gluten, which render wheat flour so superior to the 

 flour of other cereals for the purpose of panification. 



(2) The second source of variation is the quality of the 

 soil, and Mr. Richardson seems to believe that it is the most 

 important factor in producing variations in the quality of wheat. 

 The number of States in which experiments were conducted is , 

 not mentioned, but it appears that in 1882 it was found that the 

 seeds of wheat of many different varieties, which were sent to 

 "be grown in Colorado, tended to produce a crop which was, on 

 the whole, richer in nitrogenous matter or protein than the 



