LUTHER BURBANK 
It is only in very recent years that California 
fruit has challenged the product of the Spanish 
orchards. 
The absorption of water by the roots of the 
tree, and its elevation through the trunk to supply 
the deficit made by constant transpiration from 
the pores of the leaves is a phenomenon that has 
been perfectly familiar to botanists for a long 
time. It was demonstrated experimentally by 
Stephen Hales early in the 18th century. But the 
forces that lie back of the phenomenon have been 
very little understood. 
Very recently one of the most celebrated 
American botanists has declared that the cause of 
the rise of sap in trees remains perhaps the most 
interesting of botanical puzzles. 
It is, in effect, as some one has pointed out, a 
case of water running up hill, and many botanists 
have found it mystifying that the plant tissues are 
able to withstand the pressure that a column of 
water must exert, particularly in the case of tall 
trees. 
THE RIseE OF SaP IN THE TREE 
In point of fact, however, it should be recalled 
that the sap in the tree is not carried in open tubes 
comparable to the arteries of the animal system. 
If it were in such tubes, doubtless no plant 
tissues could withstand the pressure that would be 
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