in Blechnum and Osmunda. 39 
molysis also affords striking proof that the mucilage is entirely 
contained in the endoplasm and does not arise from the cell- 
membrane, for at any stage during secretion the protoplasmic 
body may be withdrawn from the wall to which it is always 
connected by numerous fine fibrils and delicate threads, and it 
can then be plainly seen that the whole of the mucilage is 
included within the shrunken utricle (Figs, 22 and 23). 
From the point of view of visibility both the drops and 
droplets vary considerably. In some glands where the muci- 
lage is dense and the protoplasmic reticulum well defined, the 
structure is very obvious without any special preparation 
(Figs. 5, 6 , 10). In other cases the reticulum appears to be 
less marked (Fig. 20), the mucilage less dense, and the drop- 
lets but feebly defined and little developed. Such glands 
require careful observation, and a cautious and well-regulated 
use of reagents, to demonstrate that their actual structure is 
that which we have described. Other glands appear to form 
an abnormal amount of tannin (Figs. 24, 25 and 26), and these 
are the most difficult to deal with. The drops and droplets 
are never so clear in this case and are sometimes even scarcely 
to be distinguished. Finally, and as a very common pheno- 
menon, there is a marked difference in appearance between 
the cortical and peripheral mucilage (Figs. 7 and 8). This is 
mainly due to the difference in pressure with which the two 
systems meet. The first-formed drops bud out freely into the 
cell-cavity, while those produced later on, by the repeated 
basipetal formations, come into existence when the cell is 
fairly full of drops, and are thus soon exposed to great 
pressure on all sides, and being densely packed appear 
to be more highly refractive than those of the central core. 
Apart from this, the structure of both forms appears to be 
quite similar, but the density of the drops and droplets varies 
greatly. 
The cell - contents usually escape by means of a small 
localised rupturing of the wall (Figs. 9 and 27), and the 
various drops are turned out, both by the elasticity of the 
wall, the feeble contractility of the ectoplasmic remains, and 
