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Transaction*. 



turning red. Particles in the cells of the phloem islands exhibit Brownian 

 movements. The phloem islands were at first thought to be either phloem 

 or xylem parenchyma cells. Careful investigation showed that in some 

 cases undoubted sieve-tubes are present, although none were found in the 

 phloem cylinder. The walls of the sieve-tubes, as usual are thin and 

 colourless, and the sieve-plates slightly oblique. I could not with certainty 

 observe any pits in the sieve-plates, or any callus. 



The Tracheae. — In this plant, as usual, the protoxylem vessels are 

 spiral, the spiral being here from right to left. The xylem of the leaf-traces 

 consists entirely of spiral vessels. In addition to these, there are the large 

 vessels mentioned above. In many cases they are observable in the course 

 of formation. They usually occur in groups of two or three, but there may 

 be as many as six. They are the only cells of the xylem which do not 



Endodermis 

 . Pericycle 



E. cambium 



Phloem' 



O. cambium 



Xylem 

 parenchyma 



Xylem 



Medulla 



I. cambium 



Fig. 7. — Transverse section of stem, showing extra-faseiculav, interfascicular, 



and original cambium. 



contain starch. Their walls are greatly thickened and pitted, the pits 

 differing from the simple pits of fibrous cells, although in the walls of the 

 vessels bordering the fibrous cells they are simple. The pits differ from 

 ordinary bordered pits in that their walls, instead of being dome-shaped, 

 are perpendicular to the middle lamella (see fig. 8, a, b). 



Fibrous Cells. — In this plant the secondary wood consists chiefly <>f 

 fibrous cells. These have greatlv thickened walls, and resemble woodv 

 fibres more or less closely in form. There is no stratification or striatic >n 

 observable. A few are septate. The fibrous cells always contain, abund- 

 ance of starch-grains, which are large and closely packed. In places a few 

 chloroplasts are present. The cells are all about the same length. 



The nuclei are large, those of the adjoining cells being in a straight 

 line, showing there has been practically nq, displacement of the cells due 



