262 R. T. BAKER. 



vessels of the ordinary type. In the younger leaf the 

 central bundle or mid-rib is surrounded by a band of pro- 

 toxylem which in the more mature leaf becomes wood fibres. 

 This is backed by loose parenchyma, probably water storing 

 cells (Plate XXVIII, figure 2). 



The tomentum, microscopically examined, is seen to 

 consist of cup-shaped, peltate, closely packed hairs, which 

 in outline rather resemble a shallow vase or tazza, or even 

 some forms of fungus, like Stereum, with mostly a two- 

 celled stem almost as broad as the cup at the top, the 

 lower cell being the smaller and often filled with a dark 

 substance, probably manganese compound.. 



Scattered on the upper surface of the leaf were numer- 

 ous depressions, (Plate XXIX, figure 3) these in section, 

 were found to be quite different morphologically from what 

 obtains generally in stomata, which they were thought to 

 be when examining the leaf by a pocket lens. The cuticle 

 cells of the leaf were found to continue around the side and 

 bottom of this depression, and no opening or guard cells 

 were detected in the specimens examined. A kind of 

 44 anchor cell" was found at the base with one cell running 

 into the depression. It may be that this acts as a clamp 

 to close the aperture leading to the water tissue if such is 

 required. Possibly they are air pores, but more probably 

 contrivances for increasing the area of the cuticle, and 

 the "clamp" to strengthen it during expansion or con- 

 traction. 



(b) Function. — The stomata evidently being few and 

 very minute, (I was unable to detect any in my sections), 

 and the tissue of the leaf quite anomalous, efforts were next 

 made to find out what functions other than those which 

 usually obtain with leaves, are performed by those of this 

 mangrove. Studying the trees carefully in their native 

 habitat it was noticed that the stems almost invariably 



