144 Transactions. 



finds in tropical climates 1 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 solitai'y 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 alwaj'^s 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 



