40 Gardiner and Ito. — On Mucilage- cells 
by the swelling of the mucilage both of the inner layers of the 
cell-wall and of that of the drops themselves. The combined 
effect of these various forces produces a very practical result, 
and the drops escape with some rapidity from the ruptured 
gland. In ordinary circumstances water penetrates with great 
difficulty through the cuticularised wall. Thus we found, when 
testing with osmic acid, that the reagent penetrated by means 
of the basal transverse wall and by way of the stalk-cell in- 
finitely sooner than through the exposed cell-membrane. 
When therefore a rupture occurs, there is quite a rush of 
water and great swelling of all the mucilaginous structures. 
Another mode of escape also occurs (Fig. 28). In this case 
there is no rupture in the real sense of the word, and the 
phenomenon only takes place in old cells which have hitherto 
remained imperforate. The whole wall through disorganisa- 
tion gradually breaks down on all sides and the swollen drops 
quietly escape. 
We have yet fo mention a small matter of some interest in 
connection with the mucilage-glands, and this is that in Blech - 
num occidental we always found a fungus associated with the 
growing point. The growth of the mycelial filaments pro- 
ceeds pari passu with that of the young shoot, and even 
manages so to distribute the numerous hyphal branches 
over all the young structures that, by the time the various 
mucilage-cells are ready to rupture, there is always some 
attendant hypha near at hand. As soon as the contents have 
escaped, this hypha grows into the ruptured cell by means of 
the orifice and soon makes strong growth, obtaining apparently 
much sustenance from what remains of the ectoplasm and 
nucleus (Fig. 30). We have not cultivated this fungus and 
are consequently unable at present to state any further 
details. 
Before concluding our description of Blechnum occidentale 
we may perhaps make some remarks concerning the resin- 
gland-cells. We have already described their development 
and stated that their structure is somewhat simpler than that 
of the mucilage-glands. It is a matter of great interest that 
