222 The Revolutionist Occupation of La-chi-mi 
peeped out here and there in delightful contrast to the 
semicircle of brown hills which rose up behind. This was 
our last day in the Mekong valley, though in order to 
complete the long stage to Shui-kin we were compelled to 
continue for some hours after dark. 
Between the monstrous slopes of brown grass with their 
parks of oak and pine we now crossed deep shady gullies 
crowded with a much richer and more varied vegetation 
than anything we had seen hitherto. In one spot where 
the river narrowed considerably the rock-strewn slopes of 
this sunless gorge were clothed with jungle, where to my 
astonishment—for we had scarcely left one of the detest- 
able regions of grass—the trees were wrapped with climbing 
Aroids and supported numerous bird’s-nest ferns. Still 
more surprising, cascades of magnificent orchids, including 
a fine species of Cymézdium, hung in full bloom over 
the screes lighting up the dark forest as though by 
magic. 
Ten minutes later we were out in the full glare of the 
sunshine again, and ferns, orchids, and forest had all dis- 
appeared as abruptly as they had come. 
Still it was evident that we were approaching a region 
where, under favourable conditions, a monsoon vegetation 
was able to establish itself, though it was equally evident 
that so long as the Mekong valley consisted of a deep rent 
torn between high mountains, this vegetation could only 
exist in such small quantity as in no wise to affect the general 
appearance of the valley. In these deep ravines it is not 
because the rainfall is heavier—which it manifestly cannot 
be—that the vegetation is so luxurious; it is simply that 
here the sun never penetrates, and the heavy dews preci- 
pitated in a region of intense radiation are able to keep 
the vegetation moist throughout the day, whereas in the 
main valley the dew is sucked up as soon as the sun 
appears over the ridge. 
As already stated we pursued our way long after 
sunset, the night being perfectly clear and calm. For 
some time we proceeded in darkness, but when at last 
the full moon appeared over the ridge, such a flood of 
brilliant light flashed into the valley that we could almost 
have seen to read small print. It was a wonderful sight to 
