TISSUES. 173 



epidermis soon breaks or bursts as the stem or shoot 

 grows larger, and is changed into, or its place is 

 taken by, the tougher, thicker, and at last hard and 

 brownish tissue, which we commonly call bark, but 

 about which I will tell you a little more in the next 

 chapter. 



(3) W^ come now to an important system or 

 arrangement of tissue, which is made up of both cells 

 and vessels. You have noticed it often in the veins 

 of leaves. These so-called veins are really bundles 

 of tissue, harder than the rest of the substance or 

 tissue of the leaf, and passing from the leaf into and 

 down the branches and main stem like bundles of 

 string or cord. When all the rest of the leaf has 

 perished, these bundles of tissue often remain, and 

 form the skeleton leaves which are so delicately 

 beautiful. If you break a stem of the common 

 plantain leaf, or pull the leaf in two, you will 

 probably see these bundles of tissue projecting very 

 plainly. But you have noticed them also in the 

 fibres of nettles (p. 51) ; and now I think I can tell 

 you what this combination of cellular and vascular 

 tissue is called. Because its cellular tissue is largely 

 prosenchyma (p. 168), and the cells particularly long, 

 thickened, and tough (fibrous), it is specified by the 

 word fibro, and so the combination tissue is known 

 as fibro-vascular* 



* From the Latin *' fibra, " a thread ; to mark the thread or string- 

 like character of most of the cells of the cellular tissue. For " vascular," 

 see p. 169. 



