By Thomas Andrew Knight, Esq. 449 



practice above described of planting large sets ; because the 

 old tuber is often found to have lost little in weight, when an 

 early crop is taken up in an immature state : and it has 

 thence been inferred, that a very small part only of the matter 

 of the old tubers enters into the composition of the new. 

 But I believe a false inference has in this case been drawn, 

 and that, under ordinary circumstances, a very large portion 

 of the soluble matter of the old tubers is employed in the 

 formation of the new ; for I have proved by experiments 

 purposely made, that the vital union, and community of 

 circulating fluid, between the old tuber, and the plant which 

 has sprung from it, is not so soon dissolved. Some Potatoes of 

 rather large size and early habit were placed in such situations 

 that the fibrous roots only of the plants entered into, or were 

 in contact with, the soil. Thus circumstanced, an abundant 

 blossom appeared, and seeds would have been produced in 

 the manner I have described in a former part of the Horticul- 

 tural Transactions ;* but both the blossoms, and the runners 

 which would have formed young tubers, were alike removed. 

 The old tubers, though fully exposed to the sun and air, still 

 retained life, and were obviously supplied with moisture by 

 the stems, which had sprung from them : and the result was 

 ultimately just that which I had anticipated. The plants, 

 after many frustrated efforts to produce blossoms and tubers 

 upon every part of their branches, at last threw their sap 

 back into the old tubers; and a numerous crop of young 

 tubers was suspended from the buds, or eyes, of the old. 

 This did not occur till autumn ; and therefore the vital union 

 must have subsisted through the whole summer ; and I enter- 



* Vol. i. page 58. 



