274 Ewart. — On the Stamina l Hairs of Thesium. 
being no longer connected with one another, but forming iso- 
lated patches, one on either side of the insertion of the stamen. 
Many pollen-grains may usually be seen adhering to the 
free ends of the staminal hairs in both instances, especially in 
older flowers after the terminal caps have become detached and 
the hairs emptied and collapsed. Two such hairs with the 
accompanying pollen-grains are shown in Fig. 4. 
In Thesium debile , where the free portions of the staminal 
hairs are much thinner and longer than in either of the above 
cases, I noticed one hair in which the terminal cap had not 
been completely separated, but remained attached at one side 
(see Fig. 5, iii). From the general appearance of the hairs in 
all the species I examined it would seem that the secretion is 
always liberated in this remarkable way, though owing to the 
preservation of the material in spirit, or by drying, the par- 
tially detached minute caps may have been mechanically 
removed. 
In the first class of staminal hairs, of which T. capittdiflorum 
and spicatum may be regarded as typical, the capped ends 
remain free and unconnected with the anthers, since they are 
inclined downwards towards the base of the style ; but in the 
second class this is not so. They are much more abundant, 
very long and slender, and form only a single group behind 
each of the stamens (as in Fig. 10), above its point of inser- 
tion. The hair-like portions pass up behind the stamens and 
usually become adherent to the tops of the anthers, sometimes 
so firmly that they cannot be detached without rupture (cf. 
Fig. 9 and 11). As types of this class the staminal hairs of 
T. debile and paniculatum , and of T. alpinum are here briefly 
described. 
T. debile. — The staminal hairs of this flower are long and 
slender and directed upwards towards the top of the anthers. 
They are arranged in five groups, one behind each of the 
stamens, the basal cushions appearing much elongated in a 
direction parallel to the surface in a longitudinal section of 
the perianth, and about two deep ; but with the longer axes 
in the opposite direction in a transverse section, forming 
