lxvi PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



several seedlings will be able to maintain their original productiveness and 

 quality. Seedling potatoes are not as a rule put ' into commerce ' until the 

 fifth or sixth year ; and it often happens that those which show the 

 greatest promise in their second or third year have been entirely surpassed 

 in the fifth or sixth year by seedlings which gave little or no promise in 

 the first, second, or third year. I remember the case of three or four out 

 of a large batch of seedlings which gave extraordinary promise, and these 

 were grown on to produce stock, but by the sixth year they had manifested 

 such marked signs of deterioration that they were not put 1 into commerce ' 

 at all ; whereas others which showed little or no promise at the beginning 

 became very popular varieties. 



" Then, as regards disease, many seedlings are very often quite free for 

 four or five years, and in the sixth or seventh year succumb to attack. If 

 all this be true of seedling potatoes before they are distributed, it 

 naturally follows that to a greater or less extent the same tendency to 

 deteriorate will be seen during the years succeeding the introduction 

 'into commerce.' Those who have facilities for raising and testing 

 simultaneously several hundreds of seedlings can, nevertheless, form a 

 fairly accurate opinion by the fifth, sixth, or seventh year as to which out 

 of so many seedlings is most likely to maintain its original vigour for a 

 period sufficiently long. "Where a comparatively small number of 

 seedlings are raised year by year, it must in a great measure be guess- 

 work as to what the future has in store for the seedlings. Undoubtedly 

 pedigree in crossing is of great value, but even when the potatoes raised 

 are the result of distinct cross-fertilisation, very few of the seedlings will 

 exhibit the distinctive characteristics of either parent, although the 

 qualities of both may be combined in many of the seedlings. I am, of 

 course, only speaking of potato crosses and potato seedlings. 



" On the other hand, a 'natural seedling,' i.e. a potato raised from 

 the seed-berry of a plant without cross-fertilisation, will often bear a very 

 close resemblance to its parent, in some cases so close as to be scarcely 

 distinguishable ; but the experience of twenty-five or thirty years would 

 certainly lead me to say that such 1 natural seedlings ' are far more likely 

 to deteriorate than those obtained by cross-fertilisation. 



" It must not be forgotten that it is extremely difficult to secure exactly 

 the parentage which potato-raisers often desire, in the first place because 

 many potatoes produce few, if any, flowers, and some others which do 

 flower produce little br no pollen, and also where pollen is produced it 

 may not be available exactly at the right moment. But for these 

 difficulties the judicious selection of parents might have a still greater 

 effect upon the seedling potatoes introduced into commerce. 



" A great deal has been said and written as to the necessity of rigorous 

 selection in order to prevent or postpone deterioration. Mr. Burbidge 

 quotes (but I believe inaccurately) Professor Hugo de Vries in support of 

 selection as a means of both improving any variety of potato and of 

 preventing its deterioration. 



" Professor de Vries, whose experimental work will be closely followed 

 by horticulturists, even though they may be unable to adopt the 

 ' mutation theory ' for the origin of species, very truly shows that any 

 crop of corn or roots consists of individuals of varying vitality and 



