56 PRACTICAL BOTANY 



III. In order to obtain a clear idea of the course of 

 these bundles, and of their connection with those of the 

 leaves, cut off a piece of the stem, so as to include the 

 insertion of a leaf or node, and about two or three 

 inches of stem above and below that point. Bisect this 

 longitudinally in a plane perpendicular to the median 

 plane of the leaf. Clear away the pith with some 

 blunt instrument, taking care not to injure the vascular 

 bundles. This process will be made easier if the stem 

 be previously boiled in water for about ten minutes. 



Now dissect out carefully the course of the several 

 vascular bundles, clearing away as much of the internal 

 parenchyma as possible. 



Treat the whole preparation with acid solution of aniline 

 sulphate for about five or ten minutes. The vascular bundles 

 will be stained yellow, and their course may then be move 

 readily followed. As in Dicotyledons generally, there are here 

 no cauline but only common bundles : this point will be 

 demonstrated by a study of the apex of the stem (see below, 

 pp. 82, 112). 



It will be apparent that in the internodes the bundles 

 run parallel to one another, and as a rule without 

 lateral fusion. This regularity is disturbed at the 

 nodes (a) by lateral fusions of some of the bundles, 

 but not of all of them, and (&) by the entry of fresh 

 bundles from the leaves (usually three from each leaf), 

 into the vascular ring. 



IV. In a longer piece of the stem follow carefully 

 the course of several of the bundles entering from the 



o 



leaves, as far as they can be traced independently and 

 without fusion. This will be possible at least for one 

 internode, and usually for two or three ; but the dis- 



