TROPICAL NATURE 



regions of polar cold or desert aridity the variety of groups 

 and species regularly diminishes ; more and more are unable 

 to sustain the extreme climatal conditions, till at last we find 

 only a few specially organised forms which are able to main- 

 tain their existence. In the extreme north, pine or birch 

 trees in the desert, a few palms and prickly shrubs or aro- 

 matic herbs alone survive. In the equable equatorial zone 

 there is no such struggle against climate. Every form of 

 vegetation has become alike adapted to its genial heat and 

 ample moisture, which has probably changed little even 

 throughout geological periods ; and the never ceasing struggle 

 for existence between the various species in the same area has 

 resulted in a nice balance of organic forces, which gives the 

 advantage, now to one, now to another species, and prevents 

 any one type of vegetation from monopolising territory to 

 the exclusion of the rest. The same general causes have led 

 to the filling up of every place in nature with some specially 

 adapted form. Thus we find a forest of smaller trees adapted 

 to grow in the shade of greater trees. Thus we find every 

 tree supporting numerous other forms of vegetation, and some 

 so crowded with epiphytes of various kinds that their forks 

 and horizontal branches are veritable gardens. Creeping 

 ferns and arums run up the smoothest trunks ; an immense 

 variety of climbers hang in tangled masses from the branches 

 and mount over the highest tree -tops. Orchids, bromelias, 

 arums, and ferns grow from every boss and crevice, and cover 

 the fallen and decaying trunks with a graceful drapery. 

 Even these parasites have their own parasitical growth, their 

 leaves often supporting an abundance of minute creeping 

 mosses and hepaticae. But the uniformity of climate which 

 has led to this rich luxuriance and endless variety of vegetation 

 is also the cause of a monotony that in time becomes oppress- 

 ive. To quote the words of Mr. Belt : " Unknown are the 

 autumn tints, the bright browns and yellows of English woods ; 

 much less the crimsons, purples, and yellows of Canada, where 

 the dying foliage rivals, nay excels, the expiring dolphin in 

 splendour. Unknown the cold sleep of winter ; unknown the 

 lovely awakening of vegetation at the first gentle touch of 

 spring. A ceaseless round of ever-active life weaves the 

 fairest scenery of the tropics into one monotonous whole, of 



