138 SCIENCE AND FRUIT GROWING 



measure of the drain caused on the trees by cropping; small, 

 imperfectly developed fruits, though weighing less than fully 

 developed ones, contain almost the same amount of food-material 

 (see p. 106), and hence the number of fruits, as well as the weight 

 of the crops should be taken into consideration. It has been 

 found in this case that, when the number of fruits is examined, 

 the alternation of + and -- signs is complete throughout the 

 whole series, with the sole exception of the occurrence of two 

 consecutive signs in 1911 and 1912. 



One external condition which has been prominent in affecting 

 the fruiting of trees at Ridgmont has been spring frost, and the 

 first question which arises is whether there is any alternation in 

 the incidence of frosts such as would account for the alternations 

 in the good and bad fruiting seasons. An examination of the 

 meteorological records from 1906 to 1915, failed to show any 

 alternation of the kind, 1 the five seasons in which such frost 

 occurred during these years marked by asterisks in the above 

 list exhibiting no alternation, and coinciding only in one case 

 (1914) with a marked deficiency in the crops. 



An examination of the general meteorological data has like- 

 wise failed to afford definite evidence that the alternation of 

 fruiting is due to alternation of meteorological conditions. The 

 data examined were : maximum and minimum air temperatures, 

 earth radiation temperatures, earth temperatures, relative 

 humidity of air, and rainfall; in each case the values for the 

 four seasons of the year, as defined in Chapter XI (p. 117), as well 

 as for two twelve-month periods, January to December, and May 

 to April, respectively, were examined separately. The possi- 

 bility of such meteorological data showing alternations in con- 

 secutive seasons should not be summarily dismissed, for, out of 

 the thirty-six series of values, there are three which give an 

 arrangement of + and signs in which alternation is decidedly 

 more frequent than it should be according to mathematical 

 " expectation," whereas in the other thirty- three cases the values 

 agree closely with this expectation : moreover, the three excep- 

 tions relate to connected phenomena, namely, the maximum and 

 minimum air temperatures in winter, and the relative air-humidity, 

 in winter also, the direction in which they all point being, that 

 a cold, dry winter is favourable to a heavy crop in the following 

 summer, a by no means improbable connection. Yet a stricter 



1 These data had not been examined at a time when a paper dealing 

 with the fruiting of trees was published in the Journal of Agricultural 

 Science (VIII, 135), and the alternation in the fruiting was there attributed 

 to alternations in the occurrence of spring frosts. 



