IXJKCTIOX KXl'KUnfKNTS OX IT.AXTX. 17 



periments on Cereus ssrpentinus (exp. 01) and 'Tr achy carpus cxceha 

 (exp. 60, PL II, Fig. 4), that SO^Cu was more abundantly present 

 in the phloem than in the xylem. In Lycopodium cernuum the 

 central cylinder, more especially the xyleni parenchyma cells which 

 enclose the vessel, contained much SO.Cu, and the cortical sclerotic 

 cells more or less of it. 



In the experiments with LiNO, solutions I ascertained that 

 litliium was chiefly found not only in the wood, but also more or 

 less in the l^ark and pith. 



In short, we may infer from these facts that the injected 

 solution is conducted most easily through the xylem elements, but 

 also penetrates the phloem parts and other tissues in some degree. 

 The rate of penetration of course varies according to the substance. 



6. IjS'JECTION method as a MEAXS for TnA('lX(r THE COURSE 

 OF A VASCULAR BUNDLE 



Many physiologists have investigated the course of the trans- 

 piration-current by placing cut branches in the solution of a 

 colouring matter (Pfeffee. 11) or by means of precipitates (Dixon, 

 JoLY, 20). As I had opportunity to observe this phenomenon, some 

 instances may be mentioned. 



A small quantity (0.03-0,15 c.cm.) of 5% SO^Cu solution was 

 injected into the petiole of Falsi a japonica on the upper side and 

 examined after a certain time. Tracing the vascular bundle which 

 contains SO.Cu (PL II, Fig. 1, C), I found that it divides into 

 some veinlets {!>') at the basal part of the blade, and they assemble 

 as if forming a plexus (c') with veinlets of other vascular bundles, 

 but again separate from one another {cV) and then run into the 

 blade as palmate veins, some grouping together where they arrange 

 themselves in horse-shoe shape (e') as seen in cross sectitn. It is 



