1916] HOFFSTADT—PIPER METHYSTICUM 125 
2. Each bundle of both the peripheral and pith rings has a cam- 
bium. The inner ones do not enlarge greatly. The outer or 
peripheral bundles lay down a ring of wood often 4-5 mm. in thick- 
ness. The proportion of xylem to phloem is about 8:1 (fig. 18). 
17 
Fics. 16, 17.—Fig. 16, detail of pericycle of P. methysticum; fig. 17, detail of 
medullary ray; C, cambium; 820. 
Late in the history of the stem an interfascicular cambium 
appears (fig. 15), which cuts off segments on the inside only; very 
late a few segments may be cut off on the other side (fig. 17). 
This closes the stem cylinder. The interfascicular cambium 
appears much later in the nodes and remains active much longer. 
