280 
SVEDELIÜS : LTFE-HISTORY OF 
solutions is rendered much more difficult by mucilage. On 
this account he considers the covering of young parts of 
plants with mucilage as a protection against destructive 
osmotic disturbances. Besides this, of course, the mucilage 
in fruits has often a more mechanical object, to effect the 
bursting of fruits, as for instance in Utricularia andin some 
other Hydrocharitaceæ, where it is formed from the seeds, or 
in Calla palustris, where according to a notice of Sernander 
(31, p. 156) it is formed by the funicle. 
As an osmotic protection the mucilage has a special 
importance for young parts of plants. This has been more 
closely investigated by Schilling (30), who has shown that 
a coating of mucilage is very common in young parts of 
plants, but disappears when they grow a little bigger. The 
same thing has been first shown by Goebel, especially in 
liverworts, where the mucilage glands at the growing 
point function only at an early stage of the development of 
the young parts of the plant. That the mucilage in the 
ovary of Enalus is to be considered as an osmotic protection 
for the young ovules is, I think, fairly evident. It appears 
directly from the fact that it was very difficult, or rather 
impossible, to make the fixing solution penetrate into the 
ovules, apparently on account of their protection by muci¬ 
lage. The period of the development of the mucilage also 
confirms this, because only when the ovaries are young— 
and thus their tissues more feeble—is there a plentiful 
secretion, but no more when the embryos are more advanced, 
and when the fruit is ripe it is nearly all gone. 
Phenomena of Pollination»— That Enalus acoroides 
belongs to that group of plants which Delpino has called 
hydrophilous has long been known. The notes in the liter¬ 
ature about its pollination all agree in stating that it com¬ 
pletely corresponds to the long-known and very interesting 
method of pollination in Vallisneria spiralis. Thus Ascher- 
son and Giirke (5, p. 244.) say in speaking of this plant 
