£80 VEGETABLE ORGANOGRAPHY. 



less visible manner : thus, for example, the centre of the 

 rays of umbels is a point where a deposit of nourishment 

 is effected, and from which the flowers draw their sup- 

 ply. In all cases flowers are developed by the ascending- 

 sap, which, in its passage, meets with deposits prepared 

 beforehand by the action of the foliaceous organs. 



The placentas of fruits enjoy the same function with 

 the greater energy as they are thicker or more fleshy : 

 thus, in several Solaneae, Rubiaceae, Primulacese, &c. in 

 Cobcea and a number of others, they are true deposits 

 of fecula, which serve to nourish the seeds. 



Finally, cotyledons themselves are often fleshy, and 

 then become true deposits of nourishment prepared by 

 the mother-plant, and absorbed by the embryo at ger- 

 mination. 



All that I have said of the deposits of mucilage and 

 fecula is equally applicable to those of fixed oil situated 

 either in the pericarp, as in the Olive, in the albumen, 

 as in the Euphorbiaceae, or in the cotyledons, as in the 

 Poppy. 



Thus, all the organs of plants are, in certain cases, 

 capable of performing a particular physiological function, 

 in becoming depositories of nutriment prepared for dif- 

 ferent growing organs ; but this circumstance, which 

 alters their use, ought only to be considered with regard 

 to Organography as a particular modification or dege- 

 neration. It is in this point of view that I have here 

 spoken of the subject, which will be treated of more in 

 detail in the Physiology. 



