189 



XXI. A CONCISE VIEW OF THE THEORY RESPECTING VEGETATION, 

 LATELY ADVANCED IN THE PHILOSOPHICAL TRANSACTIONS, ILLUS- 

 TRATED IN THE CULTURE OF THE MELON. 



[Read before the HORTICULTURAL SOCIETY, January 2, 1811.] 



THE council of the Horticultural Society having desired that I would 

 send to the society a general view of my Theory of Vegetable Physiology, 

 which has been published by the Royal Society, I have great pleasure in 

 obeying their wishes ; and conceiving that I shall be able to render it 

 more clear and useful, by making it illustrative of the proper culture of 

 some particular plant, and by referring the reader to the papers in the 

 Philosophical Transactions for evidence in support of the circumstances 

 stated, I have for this purpose chosen the melon. 



A seed, exclusive of its seed-coats, consists of one or more cotyledons, 

 a plumule or bud, and the caudex or stem of the future plant, which has 

 generally, though erroneously, been called its radicle *. In these organs, 

 but principally in the cotyledons, is deposited as much of the concrete 

 sap of the parent plant as is sufficient to feed its offspring, till that has 

 attached itself to the soil, and become capable of absorbing and assimi- 

 lating new matter. 



The plumule differs from the bud of the parent plant in possessing a 

 new and independent life, and thence in assuming, in its subsequent 

 growth, different habits from those of the parent plant. The organisable 

 matter which is given by the parent to the offspring in this case, probably 

 exists in the cotyledons of the seed, in the same state as it exists in the 

 alburnum of trees ; and, like that, it apparently undergoes considerable 

 changes before it becomes the true circulating fluid of the plant ; in some 

 it becomes saccharine, in others acrid and bitter, during germination t. 

 In this process the vital fluid is drawn from the cotyledons into the 

 caudex of the plumule or bud, through vessels which correspond with 

 those of the bark of the future tree, and are indeed perfect cortical 

 vessels J. From the point of the caudex springs the first root, which, at 

 this period, consists wholly of bark and medulla, without any alburnous 

 or woody matter ; and, if uninterrupted by any opposing body, it 

 descends in a straight line towards the centre of the earth, in whatever 

 position the seed has been placed, provided it has been permitted to 

 vegetate at rest. 



Soon after the first root has been emitted, the caudex elongates, and 

 taking a direction diametrically opposite to that of the root, it raises, in 



* See above, No. XII. f Above, No. V. + Above, No. XII. Above, No. XII. 



