^4 CIItCULATtOK at THE SAP, 



©f these, the potatoe, I obtained more interesting and decisive 

 results. 



My principal object was to prove that a fluid descends 



from the leaves and stem to form the tuberous roots of this 



plant ; and that this fluid will in part escape down the al- 



burnous substance of the stem when the continuity of the 



cortical vessels is interrupted : but I had also another object 



ift view. 



The early va- Every gardener knows that early varieties of the potatoe 



riedes .afford, never aflford cither blossoms or seeds ; and I attributed this 



soms nor seeds, peculiarity to privation of nutriment, owing to the tubers being 



because the formed preternaturally early, and thence drawing off that por- 



consumeThe ^'^" ^^ *^° ^^^^ ^^P» which in tlie ordinary course of nature 



true sap which is employed in the formation and nutrition of blossoms and 



mighthave ^^^^^^ 



formed them. , r- . / 



Cuttin-^s of the ■*• therefore planted, m the last spring, some cuttings ot a 

 potatoe ma- very early variety of the potatoe, which had never been 

 naged so as to ^^own to blossom, in garden pots, having heaped the mould 

 lubers, as high as I could above the level of the pot, and planted the 



portion of the root nearly at the top of it. When the plants 

 had grown a few inches high, they were secured to strong 

 sticks, which had been fixed erect in the pots for that pur- 

 pose, and the mould was then washed away from the base 

 of their stems by a strong current of water. Each plant was 

 now suspended in air, and had no communication with the 

 soil in the pots, except by its fibrous roots, and as these 

 are perfectly distinct organs from the runners which generate 

 and feed the tuberous roots, I could readily prevent th© 

 —afforded formation of them. Efforts were soon made by every plant 

 biosT;«m$ and to generate runners and tuberous roots ; but these were 

 ^"^"''^^ destroyed as soon as they became perceptible. An increase4 



luxyriance of growth now became visible in every plants 

 numerous blossoms were emitted, and every blossom afbrde4 

 fruit. 

 The redundant Conceiving, however, that a small part only of the tru© 

 sap was made sap would be expended in the production of blossoms and 

 on the blanches ^^^^^» ^ "^^^ anxious to discover what use nature would make 

 instead of the of that which remained, and I therefore took eflfectual means 

 roots. jQ prevent the formation of tubers on any part of the plants, 



except the extremities of the lateral branches, those being 

 the points most distant from the earth, in which the tubers. 



