Cross. — Observations on some ^eio Zealand lIalophyiei<. 565 



lU. Plagianthus divaricatus. 

 Leaj. 



Epidermis witli cells of- the ordinary type and a thin cuticle. The 

 stomata are equally numerous on both surfaces, but are not sunk in the 

 epidermis. On the lower side of the leaf are curious stellate hairs (fig. 4), 

 evidently secreting the slimy excretion found on the leaves. 



Mesophyll : («.) Palisade parenchyma in 3 layers, 2 of closely packed 

 cells, and a third of cells with larger intercellular spaces ; the chlorophyll 

 gTains are small, but rather numerous. (/>.) Spongy parenchyma is largely 

 developed, occupying two-thirds of the mesophyll ; the cells are elongated, 

 and the intercellular spaces, though large, are not so large as those of typical 

 spongy parenchyma ; the lowest layer next the lower epidermis is of shorter 

 more regular cells ; the chlorophyll grains are almost as numerous as in (a), 

 though, of course, there are fewer towards the central part of the leaf. 



Midrib has a sheath of regular cells and a well-marked, phloem. Above 

 and below it, reaching to either epidermis, are colourless cells of the meso- 

 phyll. 



11. Apium prostratum. 



Lea\. 



Epidermis consists of small cells with quite thin cuticle. Stomata are 

 numerous, though small, and occur only on the undersurface. 



Mesophyll : Two layers of much elongated, palisadic cells, with small, 

 not very numerous, chlorophyll gTains. The intercellular spaces are small, 

 and not frequent. This palisadic tissue constitutes three-quarters of the 

 entire mesophyll. The inner layer has shorter cells and fewer chromato- 

 phores than the outer. 



Vascular bundles are small, with prominent sheath and no sclerenchynia. 

 Fig. 5, (Z, shows one of the smaller veins, not the midrib. 



12. Samolus repens. 



Lea\. 



The ep'dermis consists of cells rather polygonal in outhne, with some- 

 what thickened outer walls and cuticle. Each cell contains a very con- 

 spicuous drop of oil, soluble in ether. The stomata are as numerous on 

 the upper as on the lower side. In the upper epidermis some of the cells 

 have a pinkish hue. due to the presence of anthocyan. This is not found, 

 however, in the cells of the lower epidermis. On both surfaces of the leaf 

 tiny pores are visible to the naked eye. Microscopically examined, in 

 surface-view, these appear as rounded openings, sometimes with apparent 

 cell-walls radiating from the centre. In T.S. (fig. 13, 6) it is seen that these 

 are not breaks, but invaginations in the epidermal wall. Most of these 

 are filled with greenish gTains of wax, which also appear in patches else- 

 where on the surface of the leaf. This wax is soluble in ether. In some 

 cases a few very small spherical gTeen algse were found in the wax. At the 

 bottom of each pit is a glandular hair (fig. 13, 6). The hair is divided by 

 vertical walls into several cells, supported on a swollen basal cell, evidently 

 but a modified epidermal cell. The ccills of the epidermis fining the cavity 

 are somewhat elongated. Warming (v, p. 185) mentions and figures similar 

 glandular hairs (" l-irtelhaar ") in Ghmx maritima, and notes that Ka- 

 mienski represents them in Samolus liUorahs. The hairs in *S'. repens are 

 very like those figured by Miss Ewart (iv) in Ipomcea paniculafa. They have 



