I 71 ) 
ash content. In contradistinction to the peat-bogs of temperate and cold 
gregions, which are “cold”, those of the tropics can easily be brought 
Kinder cultivation. In Java and in Sumatra many fens have thus been 
firansformed into rice-, sugar-, and tobacco fields, and can no longer 
gjbe recognized as fens by the eye. Finally tropical fens are generally 
much less accessible and a sojourn in such swamps is sometimes 
rendered quite impossible by large quantities of vermin. 
In addition to direct observation, important indicators of fens are 
the so-called blackwaters, which occur in all parts of the world, 
where peat-bogs are found. They are known to the Malay people as 
ajer itam, sungei itam, danau itam etc., but their significance is as 
little known to geographers as are the fens themselves. The black 
colour is a result of reflection, as these waters are in reality quite 
transparent and of the colour of weak tea, the colour being due to 
the humic acids and alkaline humates derived from the fens. 
The following brief survey may afford proof of the wide-spread 
distribution of fens in the Indian Archipelago, and, in spite of the 
very incomplete data, we may deduce from it that fens there occupy 
more than a million hectares. 
£ Java. The largest fen, which is found in Java, is in the 
valley of Ambarawa (residency Samarang) where its presence was 
first established by Junghuhn. A large portion of it (about 2500 
hectares) has been utilized for the cultivation of rice while the 
remainder (about 1500 hectares) at present still represents the swamp 
known under the name of Rawah Pening. From borings near Fort 
Willem I it was evident, that this fen has the enormous depth, 
unknown elsewhere, of 30—31 metres. The Rawah Pining further 
shows itself to be a true fen by the peat islands, which have 
repeatedly arisen in it, namely in 1838, 1845, 1865,1868 and 1885. 
A fen belonging to the desa Djugelangan, near Kapongan, 15 
kilometres east of Panarukan (residency Besuki) has an extent of 
21 hectares. The peat made from this contained 27,07% of ash. 
Near the desa Tuwiri-wetan, district Djenu, division Tuban (resi¬ 
dency Rembang) there is a fen with an area of 23 l / 2 hectares. The 
peat contains 25,9% of ash. 
Peat derived from a fen in the residency Bantam, of which the 
locality is not further specified, contained 36 % of ash. 
South of Meester Cornelis near Batavia several fens are found, of 
which the Rawah Pondok Tjempaka has been described in detail 
by H. C. Edeling. In the peat obtained from it 48,5 % of ash 
was found. 
Finally fens are found on the Dieng plateau. 
