THE STORAGE OF RESERVE MATERIALS 227 
As the trunk grows older similar stores of food may 
be detected deeper in the wood. These generally occur-in 
the medullary rays, either those which are the continua- 
tions of the primary ones, or others which are formed 
apparently for the purpose under discussion. These stores 
are especially for the nutrition of the more deeply placed 
wood-cells, when the ordinary constructive processes are 
in abeyance, as in the winter-time. 
Transitory stores may also be detected near the grow- 
ing points of the axis. These are due to intermission of 
growth and a consequent sudden cessation of the demand 
upon the translocation stream. The latter, instead of being 
diverted at once from the region to which it had been 
travelling, deposits in a suitably stable form the food 
which would have been consumed had not the check in 
the demand occurred. The supply is consequently ready 
to hand as soon as growth sets in again. 
Deposits of reserve materials can be observed near the 
extremities of twigs as winter appproaches. The output of 
the young leaves in the spring is greatly facilitated by the 
oceurrence of such temporary storage. It is possible by 
appropriate pruning to influence to a considerable extent 
the locality and the extent of such deposition. This is of 
very common occurrence in horticulture, the nature of 
the pruning having in this way a very considerable 
influence upon the development of floral or foliage 
shoots. 
Transitory deposits of food take place also in the floral 
organs. In many flowers which have long succulent styles, 
which must be perforated by the pollen tubes on their way 
to the ovules, there may be observed very frequently a 
deposition of food in the tissue of the style at the time 
when the germination of the pollen grain takes place upon 
the stigma. The food is then usually stored in the paren- 
chymatous tissue which surrounds the vascular bundles of 
the organ. 
Many of these reservoirs show by their structure that 
