398 The Botanical Gazette. [September, 
less extent similar conditions exist respecting potassium, 
phosphorus, sulphur, iron, and chlorine, which in fact embrace 
all the so-called mineral elements of plants. The movements 
and transformations of the two most characteristic elements 
of organic structures, carbon and nitrogen, are a little better 
known. Some progress has been made in tracing the steps 
by which the simple molecule of carbon dioxide derived from 
the atmosphere is built up into the complex, organic molecule 
of starch. But the further process by which the starch mole- 
cule combines with others to form the most complex and im- 
portant of all plant substances, protoplasm, is yet an almost 
complete mystery. The story of the progress of discovery in 
ascertaining the means by which plants get their nitrogen is 
a fascinating one, and is not yet ended. These matters in 
part lie at the very foundation of the most fundamental of in- 
dustries, agriculture. Intensive farming, and the highest suc- 
cess in the raising of all kinds of crops, is greatly promoted 
by a knowledge of the nutritive processes in plants. The 
botanists, who thirty-five years ago demonstrated that carbon 
was taken into the plant through the leaves, and not to any 
Material extent through the roots, struck a theme that revo- 
lutionized agricultural practice and added greatly to the 
wealth of the world. The more recent discovery of the con- 
as in scientific knowledge. Ample provision for its prosecu- 
tion would be a valuable investment for any people, and par- 
ticularly so for the people of the United States. 
There are many ways in which plants show similar physio- 
logical : 
mental processes upon which being and continued existence 
e throughout animate nature, but 
