SUNFLOWEK. STEM. 49 



leaves alternate, leaf-trace with 3 bundles. Cerastium t leaves 

 opposite, leaf- trace with 1 bundle. Clematis, leaves opposite, leaf- 

 trace with 3 bundles. Stachys, leaves opposite, leaf-trace with 

 2 bundles. 



The method which we have adopted in Helianthus is a coarse 

 one, and only available in stout herbaceous Dicotyledons. When 

 such a method is used we should always check our observations 

 by comparisons of longitudinal sections of the apical bud (cf. infra} 

 As a rule the subject should be studied in the first instance by 

 making such longitudinal sections. These should be thick, and be 

 cleared by treatment with dilute potash. Where the bud is not 

 too bulky Naegeli adopted the method of bisecting the bud, clearing 

 with potash, and drawing the bundle-arrangement in the two halves ; 

 hence the whole bundle-arrangement at the apex can be deduced 

 from two such sections. As a further control, series of transverse 

 sections should be cut through the apical bud ; the order of these 

 and their relative position must be accurately marked. A diligent 

 comparison of these (with drawings) will supply the data for de- 

 ducing the whole bundle-system. Finally, the results obtained 

 by these two methods should coincide, if the observations be 

 correct. 



Microscopic Observation. 



The material should he kept in spirit for some time 

 to remove resin, and air, and to harden the tissues. 

 This is not, however, indispensable, and fresh material 

 may be used. 



I. Cut transverse sections of a stem of a well-grown 

 plant of Heliantlms, i.e. of a stem more than half an 

 inch at least in diameter. 



Mount some of these in glycerine or glycerine jelly 

 (these may be kept as permanent specimens), and 

 others in Schulze's solution. Examine these first 

 with a low power (1 in.), and observe the following 

 tissues in succession starting from the exterior. 



E 



