Griffin. — Development of New Zealand Conifer Leaves. 65 



of the Podocarpece. We find none even in the more advanced 

 stages of totara, none in the early stage at least of kahikatea, 

 while we find two or three in miro. In this particular leaf we 

 find small-celled parenchyma in the place where the canal should 

 appear. The number of elements in the wood is very small, 

 and the protophloem does not form as well-marked a crescent 

 as in most of the preceding species. I was unable to find any 

 trace of isolated transfusion tracheids, but, as will be seen[ in 

 the figure, the wood tends to arrange itself out on either side of 

 the fx, and the outermost tracheids are the largest. 



Leaves of Young Plants with Cotyledons. 



We see in this leaf a tendency to elongate out at the sides 

 of the bundle. 



The epidermis has well-developed outer walls on both surfaces, 

 and there is no sclerenchymatous hypoderm. 



The stomata are still only on the upper surface, and remain 

 ho throughout the development. Hence we see that in this 

 leaf these organs never occur on the lower surface ; their position 

 in the cotyledon is advantageous in the later stages. The posi- 

 tion of the stomata on the first leaves of the different species 

 varies. In totara, in the first stage, stomata occur only on 

 the lower surface ; whilst in miro we find at this stage a few 

 still retained on the upper surface, though in the succeeding 

 stages they occur only on the lower. This brings out again 

 the early provision totara makes for the protection of its first 

 leaves. 



In the chlorophyll parenchyma we find the row of cells 

 next to the epidermis modified into palisade parenchyma, but 

 the rest is homogeneous. 



The vascular bundle is very much reduced ; there are only 

 chree or four elements of phloem and wood, and no trace of 

 transfusion tracheids. There is a small resin-canal beneath^the 

 bundle. 



The Succeeding Leaves on Older Plants. 



These gradually increase in diameter, and are triangular 

 in transverse section, except on the more mature trees, where 

 they are oval in young conical trees and four-sided on the older 

 forest forms. The increase in diameter is usually correlated 

 with a decrease in length, a provision for protective purposes. 

 The mature foliage is very like that of the mature kahikatea, 

 but can readily be distinguished by the smallness of the resin- 

 canal. The number of palisade cells in the chlorophyll paren- 

 chyma increases as the tree gets older, till in the mature leaf 

 we find this tissue arranged in rows of three, radiating out from 

 3— Trans. 



