HARDENING AND ADAPTATION 
average, the waves will go no higher than the 
point of greatest hardiness. Thus, as the work 
progresses, the plants which now and then 
show peculiar hardiness beyond the normal are 
chosen to carry forward the tests. From these 
very hardiest ones, after long breeding and 
selection come the ones which are not only to 
unite the desirable qualities of their forbears 
but which are to be fitted for their new envir- 
onment.” 
But in addition to hardening plants against 
all these —sun and ice and drought and rain,— 
they must be hardened for shipping and allied 
purposes. Mr. Burbank may have a fruit, for 
example, which matures early, is of a very 
desirable character aud would sell well at a 
long distance from its point of production. But 
it is too soft—it will not stand shipment. So 
he puts it through a long course of training, so 
to speak, and, when he is through with it, it will 
bear the long shipment and come out at the 
end of the journey as fine as when it started. 
In the production of the prune, the outer 
skin has an important bearing upon the suc- 
cess of the industry. After the prunes have 
been gathered and graded in size, they are 
201 
