COURSE OF THE BUNDLES IN THE STEM. 



273 



arranged crosswise, two larger and two smaller, the similar ones being opposite one 

 another. A few layers of cells below the epidermis a circle of eight to ten small 

 bundles is found, which run perpendicularly and separately through the internode. 



In the short thick stem of Stratiotes aloides' the bundles — all of which descend 

 from the leaves — unite 'after numerous anastomoses to one central bundle and eight 



FtG. 123.— Potaniogeton pectinatus ; end of the shoot (40). Tliiclc median section, cleared with potash, 

 parallel in the lower part to the median planes of the two rows of leaves ; higher up, from leaf 5 onwards, 

 this plane has rotated through almost 90*. Successive leaves numbered successively i — 6 ; v the opposite 

 sheathing part belonging to the correspondingly numbered leaf; s a sgitamu/a intravaginalis of leaf 3. 

 In the middle is plainly seen the vascular portion of the sympodium of vascular bundles ; the upper- 

 most bundle, which is clearly seen, goes to leaf 6 (which lies at the back of the section) ; that which goes 

 to 5 is cut transversely, since 5 was turned towards the observer, owing to the above-noted rotation. In 

 the axils of each of the leaves (up to 5) an axillary bud is plainly seen. That belonging to leaf 2 lies deep 

 in the section ; its parts are indicated by k, and the vascular bundle which enters it by * + . That belonging 

 to leaf 3 is still small: but the development of the first vascular bundle which enters it is beginning in the 

 angle where the bundle 3-I- (which nms into leafs) unites in the node with that which comes from 4, In 

 the axil of leaf i is a strongly-developed axillary shoot ; >t\ and in its scale leaves, l\ and li its two first foliage 

 leaves ; the vascular bundle which enters h is just beginning to be developed. In the axil of «2 a secondary 

 axillary shoot is appearing ; its first vascular bundle is beginning aty7 



or nine peripheral ones, 

 the internodes.' 



In the thin stolons these bundles run perpendicularly through 



* Rohrbach, /. c. p. 94. 

 T 



