SUNFLOWER. STEM. 67 



the apex ; but the various tissue-systems appear to originate 

 from a common meristem. In some cases, however (especially 

 water plants), the definition is more marked. As an instance may 

 be cited the apex of Hippuris (cf. infra, p. 82). 



Node. 



VI. Cut moderately thick longitudinal sections through 

 a young node of the Sunflower, so as to include the 

 median plane of the leaf (or of both leaves if they be 

 opposite, as they often are in the lower part of the 

 plant). Treat with potash and glycerine, and warm for 

 a few minutes [or better treat with very dilute potash 

 for twenty -four hours or more]. 



Mount in glycerine, and examine with a low power. 



The course of the vascular bundles, which appear 

 dark, is easily followed through the more transparent 

 parenchyma. Note 



1. The continuity of tissues of the stem and petiole ; 

 there is no definite boundary between these two parts. 



2. That the bundles from the petiole . pass into the 

 stem, and, curving at first inwards, they soon assume a 

 longitudinal course. 



3. That no bundle of the upper internode lies in the 

 same vertical plane as the bundle which enters from 

 the petiole, i.e. the bundle from the petiole enters 

 between two successive bundles of the vascular ring. 



4. If axillary buds be present, note how their bundle- 

 system is inserted on the bundles of the main axis, as 

 well as on those entering from the petiole. Observe 

 the large multicellular hairs seated on the apex of small 

 emergences as before seen (p. 50). 



F 2 



