THE TISSUES OF THE STEM 



5i 



of them lying isolated towards the centre, as in Molinia (Fig. 119, 

 p. 185). But in sections of Palms, Maize, and Sugar-Cane such 



Fig. 28. 



Young shaft of Schoenus nigricans cut transversely : centrally is the pith, 

 surrounded by an irregular ring of vascular bundles. The dotted patches near the 

 periphery are mechanical tissue. ( x 35.) 



strands appear more numerous, and they are seen to be scattered 

 throughout the pithless stele (Fig. 29). This is a consequence of the 



4tw ,4 



.1/72 



jtn 



Fig. 29. 

 Transverse section of an internode of Zea. 

 Mais. pr = primary cortex. />c = peric\rle. 

 o> = vascular bundles. gc = conjunctive paren- 

 chyma ( x 2.) (After Strasburger.) 



Fig. 30. 

 Diagram showing the course of the vascular 

 bundles of the "Palm type" of Monoco- 

 tyledons. The numbers indicate tlie suc- 

 cession of the alt. mating leaves. m= median 

 bundle. (After De Bary.) (From Strasburger.) 



