ON THE PINES OF AUSTRALIA. 151 
little comment. It consists of spongy and palisade paren- 
chyma and both are clearly defined in Figs 1to14. The 
latter vessels consist of a single row having the long axis 
at right angles to the dorsal surface of each leaf, but 
cease at the ventral curve. The thick walled hypodermal 
cells are so to speak the epidermal cell companions of these, 
as they also only extend as far as the epidermic and palisade 
cells and gradually diminish in size and finally give out, as 
they approach the ventral surface. They are largest and 
thickest walled at the apex of the dorsal curve, and gener- 
ally number about 100. The epidermal dorsal cells may be 
described as rectangular, and like the hypodermal ones are 
largest at the dorsal apex where the outer cell wall or 
cuticle is much thickened. They are not so numerous as 
the hypodermal cells, 50 being about the limit. 
The cells of the ventral surface take quite a different 
form from that of the dorsal ones. As they turn, so to 
speak, to curve into the ventral surface, the thick cuticle 
wall gradually domes until in the centre of the ventral 
cavity of the concrescence they reach their maximum 
height, becoming quite conical in shape—the elongated 
apices appearing to resemble numerous processes. This 
unusual structure as far as we are aware has only been 
recorded in one other instance in Conifers, i.e., Sciadopitys 
verticillata, S. and Z. of Japan.’ 
The functions of these elongated bodies (sic appendages) 
is probably (1) to assist the guard cells in the performance 
of their duties orduty. (2) They also indicate the presence 
of the stomata, being only found along with them. (3) A 
protective character for the stomata by closing over them 
as occasion requires during adverse climatic or other con- 
ditions. (4) Ovule protectors, for in the transition of the 
leaf terminations into cone scales, these elongated cells 
' C. E. Bertrand, The Gnetacee et Conifere, pl. x, figs. 10, 11, 12. 
