Griffin. — Development of New Zealand Conifer Leaves. 53 



pits on their walls. This seems to point to the fact that some 

 at least of the outer transfusion elements are formed from 

 modified parenchyma. 



The presence of bordered pits in the transfusion tracheids 

 seems constant in this species, where they occur in the maturer 

 stages on the oblique transverse walls, being plainly seen in trans- 

 verse sections. The character of these tracheids varies, as does the 

 character of the wood. In the cotyledon they hardly difEer at all 

 from the wood of the bundle, except in length ; in both cases 

 there is present a great amount of spiral thickening on the walls. 



It may be noted here that the above remarks in no way 

 detract from Mr. Worsdell's important discovery concerning 

 the presence of centripetal wood in Conifers. The investigation 

 of these species has added further evidence of this, though this 

 wood is not so markedly developed here as in species described 

 by Mr. Worsdell. What the writer has endeavoured to show is 

 that Mr. Worsdell has carried his discovery too far when he 

 ascribes the origin of transfusion tissue in all gymnosperms 

 to centripetal wood, and to that alone. 



The next two species are of a very similar nature to tlie one 

 I have just fully described, but, as a rule, are much simpler. 

 In parts, for briefness and clearness, I shall give the description 

 more in the form of notes. 



Podocarpus ferruginea (Miro). 



In most respects this leaf is much simpler than P. totara, for 

 we do not find such marked modification for protective purposes, 

 nor such highly differentiated parenchyma in the earlier stages. 



The first two leaves of the seedling, as in totara also, are 

 placed opposite one another, alternating with the two cotyledons, 

 and standing out at right angles from the stem. The succeed- 

 ing leaves arise also in alternate pairs, but lie almost in the 

 same plane as the stem ; hence we get apparently a single row 

 on each side of the stem ; but even in older plants we can trace 

 four rows of leaf-bases down the stem. 



Cotyledons. 



The cotyledons of miro die much sooner than those of totara ; 

 they remain only till the young plant has six or seven leaves to 

 assimilate for it. The cotyledons of which I cut sections were 

 growing under a large miro in moist and shady conditions. 



In transverse section they are a great contrast to those of totara. 



In the epidermis we find only slight development of cuticle, 

 and only slightly thickened walls in the epidermis — thicker on 

 the under surface, which in germination is the more exposed. 



