232 Rerort oN Crop PRODUCTION OF THB 
CHEMICAL ELEMENTS IN PLANTS. 
One of the questions which early engaged the attention! of 
chemists and plant physiologists was the determination of the 
number and function of the elements necessary for the growth 
of plants. Numerous investigations, few of which have been 
conducted within recent years, have, without question, justified 
the conclusion that at least eleven elements are essentially in- 
volved in the normal development of agricultural plants. 
Whether or not certain others, ordinarily found in vegetable 
tissue, are requisite to the functions of plant life, or at least to 
its well being, is a question which so far does not appear to have 
been definitely settled. Moreover, concerning the necessary pro- 
portions of the mineral ingredients of plants no satisfactory con- 
clusions seem to have been reached. It does not yet appear, 
for instance, that, because wheat takes up sodium, this species 
of grain must have this element in order to attain full develop- 
ment, or that when a certain quantity of potassium is found in 
a particular wheat crop, less of this element might not have met 
all requirements. Our present state of knowledge allows us to 
infer that a plant in appropriating raw materials for construc- 
tive purposes may exercise a selective power not strictly in ac- 
cordance with its exact needs. It may possibly absorb materials 
unnecessary either in the kind or in the quantity used. Notwith- 
standing all this, it is clearly established that all the elements 
of the organic part of a plant are absolutely essential to growth 
and that in the absence of some of those found in the ash, growth, 
if it takes place at all, goes on abnormally. 
POTASH AND SODA. 
Since the earliest investigations of thirty years ago or more 
it has been taught that agricultural plants cannot attain normal 
development in the absence of potash. Concerning the essential- 
ness of soda.to plant life, more or less doubt still exists. It is 
generally believed by agricultural chemists that if it is necessary 
at all, only minute quantities are needed. While these views 
