FRUIT-GROWING AND PRESERVING. 57 



Avhatever the original root treatment adopted, a complete new 

 root -system was formed in the " collar " region of the tree, 

 just below the surface of the soil. In sand (with excellent 

 conditions of aeration) all parts of the root -system gave rise 

 to an abundance of new roots; and in water culture (with bad 

 conditions of aeration), while the same thing happened at the 

 outset, the trees rapidly became unliealthy, new root formation 

 ceased, and death in many cases resulted before the end of the 

 summer. WTiile these results must at present only be considered 

 as applying to trees worked on root -stocks which produce fibrous 

 roots freely, it appears obvious that aeration is one of the 

 primary factors in influencing the production of new and healthy 

 roots, and that, given aeration, a root-system of the type indicated 

 which has been severely handled before replanting will not 

 adversely affect the further growth of the tree, provided the 

 " collar " region is not damaged. Before planting fruit trees, 

 therefore, a grower should make sure that his land is well drained 

 and well cultivated. The better the tilth, the better the aeration of 

 the soil from above, and the more healthy are the trees likely to be. 

 In a further investigation an attempt was made to trace the 

 course of development of the root -system of a plant throughout 

 the growing season. Two series of experiments were carried out, 

 but a description of the method employed would involve the 

 introduction of technical terms which might be confusing, and 

 we will, therefore, refer only to the results obtained. It was 

 found that there are certain periods during the season which 

 are marked by a distinct speeding up of root-growth, and that 

 these periods appear to be closely related to the amount and 

 distribution of organic food reserves within the tree. The 

 beginning of the growing season is marked by a vigorous root 

 development, which seems to coincide in point of time with the 

 circulation of the reserve food material which was stored in 

 the tree as the result of the previous season's growth. Wlien 

 these reserves are exhausted — the plant then being dependent 

 in respect of new growth on organic food manufactured in the 

 leaves— the shoot portion, being nearest to the source of food 

 (the lea\-es) apparently gets the first call on supplies, and the 

 tendency is therefore for shoot -growth at that period of the 

 season, namely, at midsummer, to outstrip root-growth. This 

 state of affairs is soon followed by a period when the roots are 

 presumably unable to supply sufficient sap for the manufacture 

 of material for the maintenance of such a vigorous shoot -growth ; 

 at any rate the latter is slowed down, and root formation again 

 sets in, seemingly because food reserves have again had a chance 

 to accumulate and circulate to the root. 



