nS BOTANICAL GAZETTE [august 



the nodes are swollen and marked with several distinct rows of 

 spots; the internodes are 5-9 cm. long and when young are covered 

 with dense rows of hairs, giving a ridged appearance; the older 

 internodes are smooth but spotted. 



The younger stems and nodes were cut in paraffin at 25-30/* 

 and complete series obtained. The largest stems and nodes were 

 treated with hydrofluoric acid for one week and then sectioned at 

 30-50 n with a sliding microtome, in this case also the series being 

 complete. The safranin Lichtgriin stain was used. 



Origin and course of stem bundles 



The stem of Piper methysticum contains at maturity three 

 rings of bundles, one peripheral and two within the pith, the bundles 

 being foliar. The terminal bud is enveloped in the sheathing 

 base of the youngest leaf. In some cases a bud was found within 

 the sheath of a single leaf with as many as 3 leaves, each of which 

 was inclosed in the base of the petiole just beneath it. 



The leaf primordium appears on the stem tip early and forms 

 about it a semicircle, and 5-7 procambial strands are soon differ- 

 entiated. These connect with the first strands of the stem (figs. 

 2-4, j—p). Strands j-p are the strands of the youngest leaf 

 (node 1) ; k is the first to be differentiated; j and / follow quickly; 

 and p come last. The bundles of the second leaf (node 2) are 

 represented by the series a-i. At node 1 the stem contains a 

 single row of scattered bundles. These bundles (j-p) become the 

 inner bundles of the stem at node 2, and a-i of leaf 2 become the 

 peripheral bundles (fig. 5). Through the following internode 

 these two sets of bundles run approximately parallel and become 

 the inner rings of the next node (node 3, fig. 6). The union of the 

 two inner rings takes place here. Five methods of joining were 

 observed in the case of the undifferentiated strand: (1) two strands 

 from the same ring may join (fig. 8, lm); (2) two strands from 

 different rings (fig. 7, ak); (3) one strand may divide and join 

 a strand of a different ring (fig. 7, g 1 p); (4) two strands from the 

 same or different rings may unite and then join a branch of a strand 

 from either ring (fig. 9, efg, ino); (5) three strands may join, the 

 result of this, for a short time, being a single inner ring (figs. 9, 

 10, dim). 



