— 144 — 



not all forms possess a preli- 

 minary solid cylinder, since 

 in Rubus sp. one cannot ob- 

 serve a trace of it. 



Concerning the develop- 

 ment of vascular bundles, 

 one can distinguish the fol- 

 lowing types. 1. The vas- 

 cular bundles are similar in 

 shape and development (e. g. 

 Fagus). 2. The leaf-trace 

 bundles, particularly the 

 middlemost are the larger 

 (e. g. Alnus). 3. The vas- 

 cular bundles between the 

 leaf-trace bundles are often 

 rudimentary and at an early stage swallowed up by the so-called 

 interfascicular tissue (e. g. Euonymus, Potentilla). 



Fig. 5. Rubus Idæus: Transverse section 

 of a part of the central cylinder; young 

 vascular bundle. X c. 550. 



Fig. 6. Hypericum quadrangulum : Transverse sections of parts of the 

 central cylinder; young vascular bundles; X c. 550. 



On the whole, the interfascicular vascular tissue is in many 

 cases not much developed or entirely wanting. When separate 



