HORTICULTURAL JOURNAL. 269 



is colorless and transparent, it has no openings and contains fluids, and in 

 those fluids there are different substances, the productions of vegetable life, 

 either in solution or in a solid state. The membranes take up fluids exter- 

 nally particularly water ; they bring them into the nearest vesicles or cells, 

 and in this way the fluid, which the outer cells of the root take up from the 

 ground, is carried up and circulated in all directions through the whole plant, 

 and becomes the source whence are formed all the different organs of which 

 the plants consist ; and though all are formed upon one and the same prin- 

 ciple, however, each is separately modified to discharge a more or less deter- 

 mined service, and to contribute its particular part in maintaining the organ- 

 ism of the whole. So the root has functions to perform quite other than the 

 leaves, and again these serve to other purposes than the flower, the fruit, 

 the seed, &c. Though the membranes which surround the cells are shut, 

 and have no openings at all, yet they are pervious to fluids. This property 

 is common to membranes of the bodies both of animals and plants. The 

 most simple examples prove this. If I expose in the air a bladder filled 

 with water and well closed, all the water will be lost by evaporation on the 

 surface, and the bladder will fall together, though it has no openings. The 

 thinner the membrane of the bladder, the sooner all the fluid will be lost. 

 If we expose membranes with each surface to different fluids, they pene- 

 trate through the membranes and mix with each other. The degree in 

 which this takes place depends greatly on the nature of the substances 

 which are used ; the thinner fluids penetrate, however, in greater proportion 

 than the thicker ones. This may be proved by a calf's bladder, half filled 

 with the white of eggs, which, when put into water, being put into an albu- 

 minous fluid, will become empty and fall together. This is no doubt a re- 

 markable property. The cavity which contains the thicker and more gluti- 

 nous substance, admits through the membranes of the cell a more fluid one. 

 The same is to be observed in this respect in the membranes or vesicles of 

 animals, and in the cells of plants. Gum, slime, sugar, albuminous and 

 other substances are found in a smaller or larger quantity, in the cavities of 

 the young cells of all, particularly younger organs ; they are also present 

 in those of the outer points of the root, which takes up from the soil a 

 moisture, consisting chiefly of water, mixed with small quantities of different 

 substances, soluble in that water. The moisture from the earth, being 

 thinner than the fluids in the cells, penetrates the membranes of the cells 

 in the roots, and with it those substances, the nature of which allows them 

 to penetrate through the membrane, and to fix and unite with the sap are 

 admitted into the cells ; whereas, on the other hand those substances, which 



