SECTION IV. 



405 



Mr Knight, should he false, yet the account ■which he gives of the 

 progress and agency of the sap, and proper juice, short of circulation, 

 may he true. The sum of the account is as follows : when the seed is 

 deposited in the ground, under proper conditions, moisture is absorbed 

 and modified by the cotyledons, and conducted directly to the radicle, 

 "which is by consequence first developed. But the fl.uid which has 

 been thus conducted to the radicle, mingling no doubt with the fluid 

 which is now also absorbed from the soil, ascends afterwards to the 

 plumelet, through the medium of the tubes of the alburnum. The 

 plumelet now expands, and gives the due preparation to the ascending 

 sap, returning it also, in its elaborated state, to the tubes of the bark, 

 through which it again descends to the extremity of the root ; not only 

 forming in its progress new bark, and new alburnum, but mixing also, 

 as Mr Knight thinks, with the alburnum of the former year, where 

 such alburnum exists, and so completing the circulation." — Physiolog. 

 Botany, vol. ii. p. 244. See also, on the same subject, Kieser, Organ, 

 des Plantes, pp. 258, 259, &c. 



This note has been extended to an unusual length ; but I conceived, 

 that it would be interesting to the young planter, to have a brief 

 account of the principal theories which have been formed of the circula- 

 tion of the sap, and the ultimate conclusion, to which late writers have 

 come, as it is one of the most obscure, though important processes, in 

 the whole of vegetable economy. 



Note III. Page 92. 



Although trees, as is said in the text, have no organs analogous to 

 the mouths of animals for receiving their food, yet perhaps it may be 

 said, that animals sometimes take in their food like trees. Men, for 

 example, have been known to become so debilitated by age or disease 

 that they could receive no food by the ordinary organ of the mouth. 

 The consequence has been, that they were immersed in milk and veal- 

 broth baths, and fairly subsisted by means of absorption. Thus, every 

 one of their pores became like leaves for the introsusception of food. 

 Some few years since an instance occurred in a noble Duke of sporting 

 notoriety, who was so supported during the last months of his life. 



Note IV. Page. 95. 



Opinions quite opposite to these are entertained by Dr Yule, and also 

 by Sang, who is a nurseryman and a planter of some experience ; but 

 they are not borne out by facts. The author of the Encyclopaedia of 



