11 June, 1917.] ApTple Culture in Victoria. 341 



aud other matters in higher proportions than does the crude sap, as a 

 result of the transpiration of the superHuous water from the leaves. 

 This renders it denser than the sap prepared to be taken in from- the 

 soil. In the endeavour to establish an equal density between the sap in 

 the tree and that without osmosis continues actively during the period 

 of growth. 



-Plate 92 gives the point of tlie root illustrated in Plate 91, Fig. 1. 

 But, as it is much more highly enlarged, the cells which build up the 

 root in the direction of its length are more clearly shown. 



As the walls of the cells of a feeding root consist of a very delicate 

 membrane the sap taken up from the soil passes freely through it on to 

 the sap-wood of the stem and branches, and thence to the leaves, whcc 

 it mixes with the gaseous food taken in from the air. 



Plate 98. — Leaves of a Jonathan tree, showing development. 



The Stem. 



It has been stated that the sap-wood forms the channel through 

 which the sap passes from the feeding roots up to the leaves. 



Plate 93, Fig. 1, illustrates a cross section of the stem of a one-year- 

 old Joiuitlian tree, the natural size of the section being 3-16 inch in 

 diameter. The pith is (a), sap-wood (b), cambium (c), bark (d), and 

 the parallel bundles of strands which run longitudinally and radiate 

 outwardly is the medullary rays. During the first year of the growth 

 of the stem the sap passes up through the pith, the cells of which show 

 so distinctly in the illustration, as well as through the sap-wood, while 

 the cambium gradually moves outwards. During the second and suc- 

 ceeding years, however, little or no sap passes up the pith or through 

 the hardened wood. 



