THE FRUITING OF TREES 139 



examination of these results, whilst not disproving the existence 

 of alternations, afforded no satisfactory evidence in its favour. 



There can be but little question, however, but that the initial 

 occurrence of a specially good or bad fruiting season must be 

 the consequence of some meteorological condition, and that 

 such conditions may also intensify the alternations of the fruiting, 

 without there being any alternation in the meteorological con- 

 ditions themselves : just as the swaying of the branches of a tree 

 may be originated and intensified by wind, although there may 

 be no regular alternations in the gusts of the wind. It would 

 appear, however, so far as the investigation has been carried at 

 present, that some such correlation does probably exist between 

 the fruiting and certain of the meteorological factors,* notably the 

 mean maximum temperatures during the twelve months preceding 

 the fruiting season. 



Heavy cropping in one season must cause a drain on the 

 resources of the tree adversely affecting its cropping in the 

 succeeding season, and any external conditions which resulted in 

 exceptionally heavy bearing one year (or the reverse) would 

 initiate an alternation of good and bad fruiting seasons for the 

 future, though the regular sequence of such seasons would be 

 liable to be upset occasionally by exceptional external conditions, 

 just as the records show that they have sometimes been upset. 

 Moreover, though the majority of varieties would be affected in 

 the same way by the external conditions, they would not neces- 

 sarily all be so affected, so that some varieties might show heavy 

 cropping in the seasons when the majority showed light cropping, 

 and vice versa : the records prove that this, also, does occur. 



It ma}' appear at first sight that an alternation in good and 

 bad fruiting seasons is inconsistent with the fact, previously 

 established, that similar neighbouring trees show little or no 

 tendency to alternate in their relative behaviour in consecutive 

 seasons. There is, however, no real inconsistency here. The 

 effect of meteorological conditions on the fruiting of a plantation 

 may be very great indeed, ranging from the production of a crop 

 which overloads the trees to breaking point, to the absence of 

 any crop at all; and such differences would be ample to set 

 up an alternation in future years; whereas in the case of two 

 similar trees, growing side by side, and subject to the same 

 conditions, the differences in their relative behaviour would, on 

 the average, be very small, and quite insufficient to set up any 

 appreciable alternation. 



How far a thinning of the fruit in years of plenty may be 



