ox THE ANATOMY OF MAGNOLIACE^. j^^;^ 



present 1)ordered j)its of various forms, nn^re numerous on their 

 radial than on their tangential surface ; and round pits are mostly 

 present on the tangential surface, while elliptical forms predominate 

 on the radial surface. Tlie primary medullary rays are very broad, 

 consisting of several rows of cells. 



The parenchymatous cells of the pith have thick lignified walls, 

 which are pitted, and there is no trichoblast, though the ojjposite is 

 stated to be the case by certain writers.^ 



Petiole. — The general structure is similar to that of the stem. A 

 great many trichoblasts are found in the external cortex. The 

 fibro-vascular bundles are so arranged as to present a somewhat 

 semi-lunar form with its concave side turned to the upper side of the 

 petiole (PI. Ill, Fig. 7). The bundles are rather scattered in the basal 

 portion of the petiole, but in the other portions they are more closely 

 united. There exists at the external limit of the phloem the scleren- 

 chyuiLitous sheath, but it consists of unlignified fibres. 



Blade. — The contour of the epidermal cells is not wavy here as 

 in the leaves of many other plants. The cuticle at the entrance 

 of the stoma is elevated, and presents a cup-like appearance (PI. Ill, 

 Fig. 10). The j^alisade-parenchyma of the upper side of the 

 blade consists of three or four layers of cells. Trichoblasts are met 

 with in the region where the structure of the blade is loose, so that a 

 number of intercellular spaces are left. The tibro-vascular bundles of 

 the midrib are semi-circularly arranged, and a group of sclerenchy- 

 mntous fibres is found in the cortical region lying on the l)undJes. 

 The cuticalar ridges of tlic midrib are wanting'. 



lioot. — The general structure of the (^Ider root does not nmch 

 ditfer from that of the stem. Trichoblasts are abundantly found in 

 roots a little older, but their form is much simpler than that of those 



1 Enyk'i- und I'mutl, I)ic uatHilu-lwn I'tldinfiifamilien. 



