THE STORAGE OF RESERVE MATERIALS — 288 
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 growing 
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 matérials can be observed near ar the 
extremities of twigs as winter approaches. The output of 
the young leaves in the spring is greatly facilitated by the 
occurrence 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 
they are only intended to compensate for regular or 
