144 ) Transactions. 
finds in tropical climates? Let us take, for instance, the cloud- 
forest of Ruwenzori, where these thoughts first came to my mind. 
Almost every day the moisture derived from the lower-lying lands 
and swamps hangs as a thick mist or cloud over the mountain 
side from 7400 to 8600 feet. When one enters this forest one is 
struck by the abundance of ferns. The most lovely sprays of 
maiden-hair hang from the banks, and ferns of all kinds, from the 
tall branched frond five feet high to the tiny filmy fern on the 
under side of a moss-covered rock, or the tongue-like forms cover 
ing old mossy and half decaying trees, abound everywhere. One 
is next impressed by the English character of some of the plants. 
A graceful meadow rue grows everywhere, and sanicle is common 
all over the forest. There is also a very English cerastium and 
others which are near our own familiar forms. After this, one 
is, I think, most impressed by the enormous number of climbers. 
They are of all sorts. Some are scarcely true climbers, but seem 
to have been carried up by mistake, so to speak, with the growth 
of the trees on which they depend. Where the natives have cut 
away some of the trees it is usual to find a solitary trunk with a 
screen of inextricably mixed climbing plants, forming a sort of 
bell round its stem. The next thing that strikes me is the dark- 
ness, and the rarity of insect life. In an ordinary forest the 
paths are alive with gorgeous butterflies. Slender-waisted hornets 
and dragon flies are always hovering about, but here it is all dim 
light and silence. A peculiarity of the leaves cannot fail to im- 
press one. They are large, sometimes enormous, and almost 
invariably take on a cordate shape. They are also thin and 
membraneous, not thick and hard. There are very few thorny 
plants in the forest. There is the inevitable smilax, and one or 
two plants which have long branches and thorns, by which these 
latter are supported, but this is unusual. One also cannot fail to 
be struck by one or two composites, senecios and veronias, which 
have become trees with trunks six inches or more in diameter. 
Thus in this forest we have to explain the following curious 
features—first, the abundance of ferns, the English character of 
the plants, the quantity of climbers, large thin cordate leaves, 
and some forms becoming trees which are usually herbs. Some 
of these are very easy to understand—thus, the dim light and 
humid atmosphere are exactly what ferns delight in. Some say 
that this sort of atmosphere and light was the climate of the 
primordial age in which plants took their orders, and certainly 
