200 Dr. Thomson on the Climale and I 'egctation of the Himalaya. 



dually, generally running nearly level for a number of miles, and then 

 rising abruptly from 1,000 to 2,000 feet. 



In ascending on the Himalaya (or indeed on any range of mountains) 

 from the base to the line of perpetual snow, the change of vegetation is 

 extremely gradual, and within a limited change of altitude barely per- 

 ceptible, any division into groups must therefore be in a great measure 

 arbitrary. Still some mode of subdivision is quite necessary for the pur- 

 pose of description, as otherwise the mind would be puzzled by the mul- 

 titude of facts. The less complicated, however, the mode of division is, 

 the more intelligible it will be ; it appears therefore quite sufficient to refer 

 the forms of vegetation to three groups, similar to the three zones inter- 

 posed between the equator and the pole, namely, tropical, temperate, and 

 arctic; or to use the term more commonly applied in the case of mountains, 

 alpine vegetation. 



There is so gi-eat a diversity in the vegetation of different parts of the 

 Himalaya, that I should entirely fail, were I to attempt to give any gene- 

 ral idea of the vegetation of these different zones. I shall therefore select 

 two particular spots, and by relating in some detail the gradual changes 

 of the vegetation in each of these, I shall, I hope, be able to give a good 

 general idea of the general appearance of the phenomena of vegetable 

 life. 



The hill station of Darjiling is distant from the plains of Bengal a 

 little more than 36 miles, the road following a ridge which ascends in the 

 first 13 miles rajudly to about 7,000 feet, and then runs gradually with 

 little change of level for the remainder of the way. Throughout the 

 whole distance the mountain sides are lined with dense foi'ests ; except 

 in the early morning, an almost perpetual mist hangs over the trees, 

 which collect and throw down from their foliage an abundant supply of 

 moisture. On emerging from the dry belt of tropical forest, the ascent 

 commences at once up a dry ridge, covered at first with the same species 

 as grow upon the plain, species of Bombax, Terminalia; Sterculia, Emblica 

 Duabanga, Alstonia, Gmelina, Bauhinia and others are abundant, with 

 many figs, some species of Artocarpus, and a proportion of bamboos. By 

 degrees a vegetation characteristic of mountain tracts, but still trojiical, 

 takes the place of those just mentioned. A Gordonia is extremely abun- 

 dant, with numerous euphorbiaceous trees allied to Mappa, various species 

 of Garcinia, the toon, (Cedrela toona or serrata,) a variety of mimoseous 

 trees, arboreous species of Vernonia and Helicia, beautiful Bauhinise both 

 erect and scandent, the latter climbing to the tops of the highest trees with 

 a trunk nearly as thick as a man. The road runs along the top, or on one 

 side of the ridge, looking down into deep valleys full of the densest forest. 

 If we leave the road to enter into these dark and moist hollows, we find 

 that there are occasionally small tracts of flat land along the banks of the 

 streams, which, however, more frequently run through deep ravines, clothed 

 with dense thickets of shade-loving trees, species of laurel, alder, magno- 

 lia, being mixed with the giant figs, which often form a great part of the 



