4 _ DROSERA ROTUNDIFOLIA. (Cuar. I. 
broader than long, but this was not the case in the one here 
figured. ‘The whole upper surface is covered with gland- 
bearing filaments, or tentacles, as I shall call them, from their 
manner of acting. The glands were counted on thirty-one 
leaves, but many of these were of unusually large size, and 
the average number was 192; the greatest number being 260, 
and the least 130. The glands are each surrounded by large 
drops of extremely viscid secretion, which, glittering in the 
sun, have given rise to the plant's poetical name of the sun-dew. 
p (Drosera rotundifolia.) 
Zs Old leaf viewed laterally; enlarged about five times. 
The tentacles on the central part of the leaf or disc are short and 
stand upright, and their pedicels are green. Towards the margin they 
become longer and longer and more inclined outwards, with their 
pedicels of a purple colour. Those on the extreme margin project in 
the same plane with the leaf, or more commonly (see fig. 2) are 
considerably reflexed. A. few tentacles spring from the base of the 
footstalk or petiole, and these are the longest of all, being sometimes 
nearly + of an inch in length. Ona leaf bearing altogether 252 
tentacles, the short ones on the disc, having green pedicels, were m 
number to the longer submarginal and marginal tentacles, having 
purple pedicels, as nine to sixteen. 
A tentacle consists of a thin, straight, hair-like pedicel, carrying a 
gland on the summit. The pedicel is somewhat flattened, and is 
formed of several rows of elongated cells, filled with purple fluid or 
granular matter.* There is, however, a narrow zone close beneath the 
* According to Nitschke (‘ Bot. 
Zeitung,’ 1861, p. 224) the purple 
fluid results from the metamorphosis 
of chlorophyll. Mr. Sorby examined 
the colouring matter with the spec- 
troscope, and informs me that it 
consists of the commonest species of 
erythrophyll, “which is often met 
with in leaves with low vitality, and 
in parts, like the petioles, which 
carry on leaf-functions in a very 
imperfect manner. All that can be 
said, therefore, is that the hairs (or 
tentacles) are coloured like parts of a 
leaf which do not fulfil their proper 
office.” 
