POTATOES 109 



with these preliminary matters we must lay stress ; it is 

 a wise plan to introduce fresh seed to the plot every 

 alternate year, and English growers will be well advised 

 to select Scotch seed when they make a purchase. The 

 Board of Agriculture says : 



" That Scotland affords a good change of seed for 

 England is undoubted, but why this should be so is not quite 

 clear. A number of influences are probably at work. The 

 growth of potatoes in many parts of Scotland is frequently 

 interrupted by autumn frosts, and the crops are lifted 

 before they are as well matured as the crops in many parts of 

 England. Now, if the foliage of potatoes is damaged by 

 frosts or some other influence before the tubers have 

 attained their full size there will be fewer big potatoes in 

 the produce, and consequently a better selection of seed will 

 be possible. In other words, a farmer will be using for seed 

 a certain proportion of tubers which, had they had time to 

 reach their maximum growth, would have passed to the 

 market as ware or saleable potatoes. It is possible that a 

 big potato has more ' constitution ' than a small one, con- 

 sequently, a small potato not yet arrived at its full growth 

 in brief, immature may contain more innate vigour than a 

 small yet fully matured potato that may have been the 

 produce of a weakling. Granting, then, that the proportion 

 of ware is greater in English than in Scotch-grown crops, it 

 is only reasonable to suppose that the proportion of stunted 

 weakling tubers is greater in English-grown seed. More- 

 over, the proportion of such tubers will tend to increase 

 from year to year, since the practice of retaining small 

 potatoes for seed insures that practically the entire produce 

 of weakly plants falls into the ' seconds ' or seed-size class . 



" This may to some extent explain why in England it 

 becomes necessary to change the seed so frequently and why 

 Scotch seed does so well in England. There is yet another 



