96 



SCIENTIFIC AGRICULTURE. 



what the woody fibre; they contain air, and their internal 

 structure differs in various plants. Fig. 2, b. 



The laticiferous tissue is that through which is circulated 

 the latex, or nutricious sap. It consists of minute, irregular 

 branching tubes opening into each other, and situated mostly 

 in the bark and under side of the leaves. Fig. 2, c. 



The epidermis, or outside bark, is formed of celluar tissue, 

 and envelopes the entire plant, except the stigma of the flower, 

 and the spongioles of the roots. In plants whose bark is rough 

 and ragged, as in the walnut and oak, it is not distinguishable. 



The delicate membrane which may be stripped from the 

 iris, or house leek, is the epidermis ; this covering of plants is 

 perforated by minute orifices or mouths, which open and close 

 by the presence or absence of light The epidermis and leaves 

 have several appendages, as glands, hairs, prickles, thorns* 

 receptacles and stings, which it is not necessary to describe in 

 this treatise. 



Fig. 2. 



[Fig. 2, Fornn of tissue, &c.; a, annular ducts; b, spiral and annu- 

 lar at intervals; c, laticiferous tissues; e, stomata of iris, vertical section; 

 d, d, green cells at the orifice; f, f, cells of the parenchyma; e, air cham- 

 ber; g, g, epidermis and stomata of yucca; h. stomata closed; the dots 

 represent small luminous bodies in the cells. Wood.~\ 



