S. Pickering 



133 



compared together consisted of three or six trees ; in which latter 

 cases the actual differences in the "numbers" given to the trees would 

 not be the same as where two trees were compared ; but the percentage 

 tendency towards the different forms of fruiting need alone be given 

 here. These are entered in the following table, the first series applying 

 to dwarf apples and pears (in smaller numbers) of several different 

 varieties at Harpenden, the others to dwarf apples at Ridgmont. The 

 dates to which the observations apply are entered in the second column, 

 and the number of instances on which the results depend, in the third 

 column. 



There can be no doubt but that the results at Harpenden are very 

 different from those at Ridgmont, for, whereas the former indicate 

 a strong tendency towards alternate fruiting, the latter, with one 

 exception, indicate a tendency, though a feeble one, towards conse- 

 cutive fruiting. The Harpenden results must however be discounted 

 to a certain extent, for the number of instances available are smaller, 

 and the period over which the observations extend is shorter than in 

 any of the other cases : also, there were some preliminary observations 

 made on these same trees in 1894-1897, when the results were of an 

 opposite character, there being 20 instances supporting alternate 

 cropping, and 30 supporting consecutive cropping. This difference, 

 however, was probably due to the youth of the trees at the time, for, 

 with trees which have not yet come into proper bearing, precociousness, 

 or the reverse, in certain individuals, would increase the number of 

 trees behaving in the same way in consecutive seasons. 



The difference between the Harpenden and Ridgmont results can 

 not, however, be explained away on any of the above grounds, and are, 

 no doubt, real. There are probably tendencies both to 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 



9—3 



