Chap. IV] TROPICAL DISTRICTS CONSTANTLY MOIST 29,3 



denser, the foliage-lcavcs smaller, and all plants, except accommodating 

 mosses and lichens, remain attached to the ground. The abundance of 

 moisture is the physiological factor of all that is characteristic in the plastic 

 form of the tropical rain-forest. 



As a matter of fact, all rain-forest districts receive not only precipitations 

 at all seasons of the year, but also very large quantities of rain. The 

 rainfall of rain-forest climate amounts to at least 200 cm. annually, but 

 frequently to very much more ; 300-400 cm. are not at all rare. The 

 atmospheric humidity is correspondingly great. It seldom sinks much 

 below (So 7^, and at night and in early morning it approaches complete 

 saturation. 



G. Haberlandt made some observations regarding the humidity of the air at 

 the edge of the virgin forest near Tjibodas. According to these observations, the 

 relative humiditj- there, even during the bright forenoon, was £0-90% at 7 a.m., and 

 in the afternoon always 97-99 %• The lowest relative humidity I observed was on 

 February 12 at noon, with a clear sky, when it was 79%- The humidity is naturally 

 still greater within the forest, where for weeks together it probably never sinks 

 below 90 °/, ^ 



iii. TROPICAL RAIN-FOREST IX ASIA. 



An account of an excursion in the tropical virgin forest may afford 

 a clearer picture of the general character of such a forest than any merely 

 general remarks on the subject. I extract from my notebook the following 

 sketch, made on the spot, of a virgin forest on the Gedeh in Java, with 

 occasional references to the forest of Salak, which is close by- (Fig. 137). 



Compared with a forest of Central Europe the picture is one of marvellous 

 luxuriance but also of confusing disarray. The stems of the trees are very 

 unequal in thickness, they are sometimes supported at their base by plank- 

 buttresses ; liancs, the stems of which are seldom thicker than the fist, traverse 

 the air in confused serpentine coils. Between the trees the brush-wood of 

 large-leaved and often gail\- flowered shrubs is frequently interrupted by gaps, 

 which are occupied by very juicy herbaceous plants often taller than a man. 

 What at first glance distinguishes the physiognomy of such a forest from 

 that of a European or North American forest is the crowding of the space 

 with foliage and the overpowering preponderance of green colour. The 

 surface of the stems of the trees is almost completely concealed beneath 

 a green envelope of plants. This covering is in places chiefly formed 

 by Freycinetia insignis, an ivy-like climbing species of Pandanaceae, the 

 shoots of which, pendent in elegant festoons and thickly covered with 

 flaccid riband-like leaves, penetrate the crowns of the trees. From the 



' Schimper, op. cit., p. 792. 

 The Gedeh forest lies in a cooler region, at about 1,500 meters, yet still preserves 

 a tropical aspect. 



