THE FRUITING OF TREES 135 



alternate and consecutive cropping, and, whether the one or the 

 other predominates, depends on the conditions of soil, climate, etc. 

 There can be no doubt, however, that the main factor determining 

 the fruiting of trees in consecutive years is neither of these 

 tendencies, but chance, that is, external conditions : with the 

 Ridgmont results, this is potent to the extent of about 90 per cent., 

 and, even with the Harpenden results, it is the predominant 

 factor. That it should be more potent at Ridgmont than at 

 Harpenden is easily explained, for the former of these stations 

 is much more subject to spring frosts than the latter, and it is 

 to spring frosts that the failure of crops is generally attributable. 



In the case of the plantation of 117 varieties of apples, there 

 were eight trees of each variety, and these were divided into 

 pairs, one pair on the paradise stock, which had been very lightly 

 pruned since they were planted, and one pair on the same stock, 

 which had been more severely pruned ; there were also two pairs 

 on the crab stock, which had been treated in like manner. An 

 examination of the results indicates that the tendency towards 

 consecutive bearing becomes more marked as the age of the trees 

 increases : thus, dividing the results into two periods, 1906-9 

 and 1909-13, it was found that the tendency in this direction, 

 taking all the trees together, amounted to 8 per cent, for the first 

 period, and 26 percent, for the second, and, further, the differences 

 were uniformly exhibited by each of the four classes of trees : 

 this is what might be expected, for any habit exhibited by a 

 plant or animal tends to become more established as its age 

 increases. As to the influence of the stock : trees on the paradise 

 stock showed uniformly a smaller tendency towards consecutive 

 fruiting (n per cent.) than did those on the crab stock (30 per 

 cent.) ; whilst as regards pruning, the results were equally uni- 

 form, the tendency towards consecutive fruiting being less 

 marked with the more severely pruned trees (10 per cent.) than 

 with those very lightly pruned (26 per cent.). Apparently, the 

 more a tree is left to natural development, the more does its 

 fruiting become conditioned by extraneous circumstances. 



In the case of observations on a plantation containing different 

 varieties of trees, it is probable that the influence of chance on 

 the bearing of the trees will be unduly exaggerated; for some 

 of the instances which counterbalance each other will consist 

 of cases where the consecutive and alternate fruiting is attribu- 

 table to the inherent properties of the trees, and not merely to 

 the effect of chance or extraneous circumstances. From the 

 results of general, though, perhaps, not very exact, observations 



