LUTHER BURBANK 
There are certain classes of juicy exudates, 
however, which appear to have characteristics that 
make them useful to plants of many types. Promi- 
nent among these are the milky juices that when 
dried constitute rubber, and the resinous ones that 
constitute tars and resins and turpentine. 
Nothing could be physically much more dis- 
similar than a piece of rubber and a teaspoonful of 
oil of turpentine. 
But the chemist tells us that each of these sub- 
stances is composed exclusively of the two ele- 
ments carbon and hydrogen; the only difference 
being that the turpentine molecule has 10 atoms of 
carbon and 16 of hydrogen, whereas the molecule 
of rubber has 8 carbon atoms and 7 atoms of 
hydrogen. 
Just how the elements are compounded, and 
just why they should make up substances of such 
unique characteristics when brought together in 
these particular proportions, even the chemist does 
not know. Nor, until recently, was he able to dupli- 
cate the feat of building up these complex mole- 
cules, even though he is perfectly familiar with the 
general properties of the atoms of both carbon 
and hydrogen. 
In very recent years, however, chemists have 
been at work on the problem of compounding the 
atoms in such a way as to get them together in the 
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