UNDESCRIBED DARWINIA AND ITS ESSENTIAL OIL. 183 



Staminodia very small, subulate, about as long as the 

 filaments. 



Style well exserted, sometimes over an inch long. 

 Histology of Leaf. 



In a transverse section the usual leaf structure of angio- 

 sperms obtains, except the guard cells of the stomata, which 

 are of rather unusual form, being shaped in transverse 

 section like the arms of a pair of callipers. 



In the centre is the midrib, proportionately small to the 

 area of the section, and surrounded by a ring of endodermic 

 cells supported by a very loose mesophyll or spongy tissue 

 which is bounded by parenchyma carrying chloroplastids r 

 followed outward by palisade layers, the whole encircled 

 by a single row of deep epidermic cells in length equalling 

 the depth of the palisade cells. Sparsely scattered through- 

 out the latter are the oil glands. 



Interpolated between the palisade and loose parenchyma 

 tissue are found elongated water storage tracheides with 

 spiral thickenings, a useful provision of nature for this 

 arenaceous plant. 



The stomata are not numerous, but are interesting, for 

 the guard cells are quite unique in shape, being curved like 

 the mandibles of some coleopterous insect or a pair of 

 callipers, the free ends in section tapering to a sharp point. 



A high magnification shows a few scattered hairs on the 

 surface of the leaf. 



Essential Oil. 



The material for distillation was collected at the Hawkes- 

 bury River, New South Wales, early in November, and 

 when distilled was quite fresh. The average yield of oil 

 from the leaves with terminal branchlets was 0*12 per cent. 



The oil was red in colour, somewhat mobile, and had 

 a terpene like odour. In general characters and appear- 



