410 Boewig on the Histology and 



other respects ordinary. The guard cells slope toward each 

 other, have large nuclei and thick cuticle, especially toward 

 the opening. The cells in the furrows connecting the 

 stomata are somewhat concave in their upper surface, have 

 thicker cuticle and are denser-looking. 



The cortex shows, at irregular intervals in the subepider- 

 mal layer, large rounded isolated cells with dense yellowish 

 contents concentrically arranged. Long-continued soaking 

 and boiling in water failed to change the appearance of these 

 contents. I have not been able to find that they extend 

 over more than one cell in longitudinal section. 



The hard bast forms perfectly homogeneous strands, each 

 element of which appears uniform in longitudinal aspect. 

 Sometimes their ends taper into each other. The bast was 

 conspicuous for its impartial reaction to stain. Safranin 

 and methyl green proved the best combination, as the red 

 set off very sharply all wood elements against the green of 

 all other parts. The hard bast alone stained red or green 

 apparently without preference. 



The outstanding feature of the wood in longitudinal sec- 

 tion is the large pitted vessels. They appear in cross section 

 as large round elements, frequently divided by branching 

 into two irregular semicircles. In longitudinal section they 

 are usually much broader than the adjoining elements, and 

 the cells of which they are compounded show their ends 

 broken through into a single large bordered pit with the 

 membrane ruptured. The lateral walls show closely packed 

 very large bordered pits, in various stages of growth. Fig. 

 9 represents a typical cell of the pitted vessels. With a 

 one-twelfth immersion lens the middle lamella is seen to 

 have quite measurable thickness, as is better shown in Figs. 

 TO and II. It is easily enough seen, even with the low 

 power lens. 



Into these pitted vessels frequent and often very copious 

 tyloses extend. These are most clearly seen when studied 

 in longitudinal section in the two Figs. lo and ii. The 



