40 BOTANY. 



dermal cells. In some cases the separable cuticle may be seen. Now 

 and then a breathing-pore may be seen in cross-section. 



(d!) Malie similar sections of the leaf of the oleander, cactus, com- 

 pass-plant, holly, or any otliersof a hard texture. Note in some cases 

 (oleander and cactus) that there are several layers of epidermal cells. 



(e) Mount in alcohol a few hairs of tickle-grass (Panicum eapillare) 

 as examples of simple one-celled hairs. 



(/) Mount iu like manner hairs of petunia, verbena, or walnut as 

 examples of hairs made of a row of cells. Note that many of these 

 are glandular. 



(fir) Mount in like manner hairs of the mullein as examples of 

 greatly branched hairs. 



78. The Fibro-vascular System. — ^In most of the higher 

 plants portious of the interior tissues early become greatly 

 differentiated into firm elongated bundles, which run 

 through the other tissues. They are composed for the 

 most part of tracheary, sieve, and fibrous tissues, together 

 with a varying amount of parenchyma, and have a general 

 similarity of arrangement and aggregation. In a few cases 

 milk-tissue is associated with those above mentioned. To 

 these collections of tissues the name of Fibro-vascular 

 Bundles has been given. They are also called Woody 

 Bundles and Vascular Bundles, but the name first given is 

 to be preferred. 



79. In many plants the fibro-vascular bundles admit of 

 easy separation from the surrounding tissues; thus in the 

 Plantain (Plantago major) they may readily be pulled out 

 upon breaking the leaf-stalk. In the leaves of plants, 

 where they constitute the framework, they are, by macera- 

 tion, readily separated from the other tissues as a delicate 

 network. In the stems of Indian corn the bundles run 

 through the internodes as separate threads of a considera- 

 ble thickness. 



80. In the fibro-vascular bundle of the stem of Indian 



