CELLULAR TISSUE. 21 



tenancc of man. 'Tis here we find deposited the material 

 that forms our bread, troin whatever jirain it may he manu- 

 fi^fiii.d. 'Tis the ccllukir tissue tilled with an amylaceous 

 lice that composes the edible part of the roots that are 

 brought to our tables. The mealiness of potatoes as it is vulixar- 

 Iv called, is but the swollen and comparatively dry cells, wliich 

 com(>ose this important vegetable ; the beet, carrot, and turnip, 

 owe their value so far as they are suited for tood, to the abun- 

 dance of this tissue, developed in the cellular integument of the 

 bark of the roots, and just in proportion as the other forms 

 are developed, they become useless. The tough, fibrous form 

 these routs sometimes assume in dry seasons, or poor soil and 

 uncultivated state, is owing to the diminished quantity of the 

 cellular tissue proper, and the abundance of the prosenchy- 

 mous or woody form. Starch, arrow-root, c^c. are but forms 

 of the same substance. The various fruits arc composed of 

 cells filled with the various juices j)eculiar to each species. 

 In the lemon we find the vcssicles filled with an acid of con- 

 siderable intensity. In the orange, and pine apple our taste 

 IS gratified by the mild yet delicious Havor of their contents. 

 In the melon we meet with a fluid of a blandness, and insip- 

 idity, almost equaling fountain water. The various coloring 

 materials drawn from the vegetable kingdom, used in the arts, 

 have their locality in the same tissue. The coloring matter 

 which produces the great variety of hues tiiat elicit our ad- 

 miration by their brillianc}' and varietj', is deposited in trans- 

 parent cells. The satiny appearance exhibited by many 

 highly coloured flowers, depends (according to Lindley,) on 

 the highly colored lluid within the cell gleaming through the 

 white shining membrane of the tissue. These subjects we 

 shall notice more particularly hereafter. 



18. The cellular tissue has of late occupied the attention 

 of the most distinguished physiologists. In common plants, 

 the opacity of the vegetable substance and the minuteness of 

 the cells preclude all examination of their functions ; hence 

 the more simple plants have generally been the objects of 

 invr ' ' 'ion. The Chara Fragilis has long been a subject 

 of ! . As early as 1774, Corti, an Italian physician of 



Lucca, discovered the circulation in the tube of the Chara. 

 Fontana, also an Italian, published in 1776 a rej)etition of 

 Corti's experiments, and the discovery of a similar circulation 

 in other plants. These curious oljservations were neglected 

 till 1807, when Treviranus observed the same phenomena, 

 beinir ignorant of the previous discoveries. In 1818, M. Amici 

 of Modena, published his observations on the circulation of 



