SECRETION IN THE HYPERICACEZR. 463 
(fig. 23). In this species the glands are not composed of so many 
cells as in H. hirsutum, but the individual cells are much larger. 
The secretion of the glands is solid and of resinous nature. 
It is deeply tinged with a violet colouring-matter, which also 
stains the cell-walls. This colouring-matter is soluble in water, 
alcohol, and glycerine. Caustic potash also removes it and 
appears further to dissolve the resinous contents of the cells. 
Certain orange-coloured or brown spots which appear on the 
sepals of H. calycinum may be confounded with these dark 
glands. These are, however, due to an accumulation of resin in 
the epidermal cells of these spots, and are not glandular at all. 
The last description of secreting-organ differs from those 
already described in being undoubtedly schizogenous in origin. 
Slender passages or ducts may be observed in the young phloém 
of the stem of H. calycinum, arising rather later than the resin- 
passages in the cortex and pith. Just after the first differentia- 
tion of the procambium, and consequently at a point in the stem 
very near the growing-point, their origin may be noticed. The 
whole mass of the procambium-cells stains more deeply than the 
cortical tissue, but the cells which are about to form the passage 
are distinctly darker than the others. I have no doubt that they 
arise from a row of single cells forming a strand, as in the case 
of the other resin-passages in the cortex; but I have not been 
able to detect in transverse section an earlier stage than that of 
fig. 24(Pl. XL.), where the single cell has divided into two. This is 
soon followed by a further division of each of the two cells (fig. 25), 
and in the centre of these four so formed a separation takes 
place (fig. 26) which forms an intercellular space. The separation 
proceeds from this point towards the periphery, the space between 
the cells enlarging, and the cells themselves becoming flatter 
(fig. 27). They differ from those of the other passages in not 
dividing repeatedly to form a mass of tissue ; in fact a section of 
the duct never shows more cells than these four lining its cavity. 
As the growth of all the tissue is vigorous at this time, the duct 
enlarges, and its constituent cells also increase in size, altering 
still in shape (fig. 28). They do not, however, keep pace in 
growth with the enlargement of the cavity but become gradually 
narrower. While the phloém remains unaltered these ducts 
persist; but when the xylem begins to increase in thickness, the 
phloém-layer becomes somewhat compressed and the walls of its 
cell are altered. Then gradually the passages become pressed 
