156 Some Experiments on the Growth of Potatoes, 



From this table it appears that while many of Mr. Knight's seed- 

 lings yield a considerable increase, the rate being in four cases as 1 

 to 28 or 29, in another case as 1 to 46, and in another, as high as I to 

 51.93, yet that the highest rate is exceeded by one English and two 

 French sorts. In a French kind called La Degeneree, it is as 1 to 

 64.57 ; in the Long Red Kidney, as 1 to 88.83 ; and in a French 

 sort called La Divergente, as 1 to 123 nearly — a most remarkable 

 instance of reproductiveness.* On the other hand it may be noted 

 that although many of the old sorts have given a very small in- 

 crease, one having scarcely yielded more than fourfold, yet that two 

 of Mr. Knight's are even more unproductive, the rate of increase 

 being in the one case as 1 to 3.34, and in the other as 1 to 3.36. 



But although the rate of increase is thus against Mr. Knight's 

 seedlings, a circumstance that may perhaps be owing to the much 

 larger size and greater weight of the tubers in his than in the old 

 varieties, yet the produce per acre is as much in his favour. And 

 this is a very important fact, inasmuch as it seems to show, what is 

 indeed not by any means improbable, that although small tubers 

 are capable of yielding under fitting conditions, as great a rate of 

 increase, or even a greater than large tubers, yet that in taking the 

 produce per acre, the heavy, sound, fully formed tuber has much 

 the advantage. 



Among the twenty-five old varieties, five only exceeded 8 tons an 

 acre, of which one produced more than 9 tons, and two more than 

 20 tons ; in one of these latter cases the rate of increase was only as 

 1 to 33.73. There were no fewer than ten sorts, that produced 

 less than two tons per acre. The twenty-five kinds averaged a 

 little more than 4y tons per acre. 



Among Mr. Knight's twenty seedlings, thirteen exceeded eight 

 tons an acre; of which nine exceeded twelve tons, and one eighteen 



• Of these varieties, La Degeneree is very large, reddish, and apt to be watery; the 

 Long Red Kidney is better, but not first rate ; La Divergente is roundish, yellow, mealy 

 and gtjod ; but they are all perhaps better adapted to Agricultural, than to Horti- 

 cultural purposes. 



