SUNFLOWER. STEM. 47 



Around this will be seen, arranged more or less 

 regularly in a circle, and near the periphery, a series 

 of more solid-looking masses of tissue, these are the 

 Vascular Bundles. 



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 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 aniline sulphate and sul- 

 phuric acid for about five or ten minutes (cf. p. 22). The 

 vascular bundles will be stained yellow, and their course may 

 then be more readily followed. As in Dicotyledons generally, 

 there are here no cauline but only common bundles (cf. Apex). 



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 



