278 Ewart —On the Staminal Hairs of Thesium . 
cushion becomes enlarged in the same direction as do the 
basal cushions themselves, so that it is difficult to draw the 
line between them when the secretion has escaped. The 
enlarged cells can ultimately be seen extending from the 
basal cushions of the hairs under the epidermis as far as 
the apex of the perianth. In T. paniculatum the side- walls 
of the empty basal cushions become plaited, but this does 
not seem to occur always in other species. 
Nature of the secretion. — I have only investigated the 
nature of the secretion of the staminal hairs in two species 
of Thesium , viz. T. paniculatum and spicatum , which had been 
preserved in spirit, since I was unable to obtain sufficient 
dried material for the purpose. However, these constituted 
typical examples of the two classes of staminal hairs, and 
the secretion appeared to be very similar in both. 
In mature flowers it is yellowish green in colour, and more 
or less clear, especially in the first mentioned, where the 
globules are more finely divided. In young hairs, and in 
T. spicatum it has a more granular appearance. 
With a one per cent, solution of osmic acid, the secretion 
stains black, demonstrating the presence of an oil ; but I 
was unable to completely dissolve it in either chloroform 
or benzole, although in the former case only a small dark 
granular residue was seen after mounting in spirit. 
With picric-Hoffmann’s-blue only negative results were 
obtained, although the surrounding protoplasm became 
deeply stained. After treating with an alcoholic extract of 
alkannin (which stains best when freshly made), the globules 
became bright crimson, and this colour could be obtained 
even after the sections had been immersed for some time 
in potash solution. It would therefore appear that some 
form of resin is present. Treatment with iodine solution 
only gives rise to a deep brown colour. 
I therefore conclude that the secretion is of the nature of 
a balsam, — a mixture of a resin and an ethereal oil ; similar 
globules are frequently to be seen in the subepidermal cells, 
where large quantities of tannin are also present. 
