338 SCIENCE AND FRUIT GROWING 



and extended over three years, the dates of planting in the 

 more important series being March 24, April 23 and May 26. 

 The results may be summarised as follows 



Early. Mid-season. Late planting. 



1896 crops . . 100 85 



1897 . .93 100 65 



showing a more or less decided advantage in favour of midseason 

 planting. The early sowing was attended with a further dis- 

 advantage than that indicated by the reduction of the total 

 crop, inasmuch as the tubers exhibited a considerable amount 

 of " growing out/' 



At the same time the effect of using sets of different sizes was 

 examined, and considerable advantage was found to lie with 

 the sets of medium size : thus 



Large. Medium. Small Sets. 



Crops . . 85 124 100 



but the size of the sets was found to have no effect on the average 

 size of the tubers in the crops. 



The relative weights of the large and small sets used in these 

 trials were as two to one. 



The advantage of -obtaining seed potatoes fresh from certain 

 districts of Scotland is well known, but there is also a very 

 prevalent belief that a mere change of seed from one locality 

 to another is an advantage, though sometimes this opinion is 

 qualified by stating that the desirable change is one from heavy 

 soil to light soil. 



In 1899 potatoes " The Bruce " were grown in the heavy 

 soil of the Fruit Farm, the seed having been obtained, in one 

 case from a crop grown in light soil at Maulden, Bedfordshire, 

 in another case from the Oxford clay soil in the neighbourhood, 

 and in a third and fourth case from crops grown at the Fruit 

 Farm itself. The results showed no advantage whatever from 

 a change of seed, whether from a light or a heavy soil, and the 

 seed where there had been no change of soil at all, gave slightly 

 the best results. 



From Light soil. Heavy soil. The Fruit Farm. 



A. B. 



Relative crops . 92 92 98 102 



A similar trial was made in 1917, but it was combined with the 

 use of seed fresh from Scotland, and all the seed used was of 



