46 Gardiner and I to. — On Mucilage-cells 
when caused by the action of water, and it is often a matter 
of difficulty during the later stages of secretion to distinguish 
the bubble-like appearance connected with the true drop- 
formation from the somewhat similarly utriculated starch- 
grains, and portions of the nucleus also. In no case does 
the whole of the nucleus disappear, but the starch-grains 
become entirely disorganised and destroyed. Not unfre- 
quently irregular lumpy masses of callus occur on the side 
walls of the cell, and equally with the callus of the transverse 
walls they appear to be formed, at least partly, from the 
starch-grains ; thus confirming the view that callus is of 
the nature of a starchy mucilage 1 . 
The mucilage of Osmunda is of the same nature as that of 
Blechnum , and gives similar reactions. Certain phenomena 
occur in consequence of the action of corallin-soda, which are 
perhaps deserving of mention. In the first place, the proto- 
plasm adheres witffgreat tenacity to the transverse walls, and, 
even after death, the main protoplasmic body is connected to 
them by numerous fine filaments. This is of some interest in 
connection with the perforation of which we spoke. Secondly, 
a number of delicate utricles arise on the free surface of the 
protoplasmic body; these appear to owe their formation to 
an external secretion of mucilage, induced by the deleterious 
action of the somewhat concentrated solution of sodic car- 
bonate (Fig. 42). 
We have already alluded to the mode of rupture of the cells 
and the escape of the secretion. The mucilaginous contents 
escape in one large mass, which soon swells and disorganises. 
Very commonly the ectoplasm and what is left of the nucleus 
remain in the cell after the secretion has escaped, and thus 
afford further proof that all the mucilage is derived directly 
from the endoplasm and is enclosed by the ectoplasm. The 
protoplasmic framework breaks down and becomes granular 
as in Blechnum. The amount of slimy and stringy mucilage, 
which results from the addition of water to the free secretion, 
1 Gardiner, in Camb. Phil. Soc. Proc., vol. v (1883), p. 230. 
