in Blechnnm and Osmunda. 41 
in the same plant, and even on the same scale, there should be 
two forms of hairs practically identical in development, dis- 
tribution, and even in their broad plan of structure, one of 
which should secrete mucilage, and the other, by some differ- 
ence (possibly a slight one) in the metabolism of its proto- 
plasm, should give rise to resin. It is a phenomenon which is 
certainly worthy of more investigation, but for the present we 
have confined ourselves to the question of mucilaginous secre- 
tion, and we can now do no more than give just the slightest 
description of the structure of the cells and the mode of 
secretion of the resin. Each cell contains a lenticular and 
very distinct nucleus, and the protoplasm is exceedingly 
granular in the functional cells, especially towards the head, 
where the nucleus and the main mass of the protoplasm is 
situated (Fig. 32). A single large vacuole is generally present 
at the base of the cell, and here the utricle is thinner and 
hyaline. The secretion collects only under the head of the 
gland, so that the bladder does not surround the whole free 
surface (Fig. 31). The resin gives the usual reaction with 
alcannin, and in certain cells it was recognised both under the 
cuticle and in the cell-contents. We think there is little doubt 
that the mode of development of the resin is similar to that of 
the mucilage, and that some formed body, produced by the 
activity of the protoplasm, is present as a series of meta- 
plasmic drops, and undergoes further changes before the final 
production of resin. 
(b.) Osmunda regalis, L. 
We have seen that in Blechnum occidentale the young bud 
is adequately protected both from mechanical injury and also 
from abnormal variations of temperature and moisture by the 
numerous paleae and by the secretory hairs of the paleae and 
leaves. In Osmunda a similar provision occurs, but the de- 
tails of the arrangement are somewhat different. In this case 
paleae are absent, and it is the base of the leaf-stalk, here 
winged and sheath-like, which acts as a protection against 
injury from without and also bears the mucilage-cells (Fig. 
