its bed. It is of course an obvious rejoinder to this, that there are also other parts of East Turkestan in which forest is absent where it might nevertheless be expected to occur. Why is there no forest, for instance, on the shores of the Tschöl-köl ? Is that lake too so recent a formation that forest has not had time to grow up ? From its position one might readily infer that it is quite old. The existence of a lake lying on the flat, as Lalmoj does, is necessarily precarious, and sooner or later it is bound to be filled up and disappear. A similar fate may well threaten the Tschöl-köl, but its existence appears to be in some way bound up with that of the Tschoka-tagh, at the western foot of which it is situated; and similarly with the Jughan-balik at the north-western foot of the Tusluk-tagh and the Schor-köl at the western foot of the Masar-tagh. Our knowledge of the meteorology of this region is too slight to justify us in drawing any definite conclusions from this parallelism. But whether it be, that the corrasive force of the wind has been intensified at the western foot of these mountains by reason of the mere presence of the obstacle, the ground being in consequence more deeply excavated there than elsewhere, or whether it is the mountains which have protected the lake-basins and prevented them from getting filled up with drift-sand and dust, it is at any rate certain, that lakes such as these are more permanent and of greater age than the marshes and marginal lakes of the open flat-land. And yet forest is absent on the shores of the Tschöl-köl! Beside the Sorun-köl, which lies to the north of it, .there stand a few solitary poplars, as there also do beside the Jughan-balik; and again by the side of the long string of marginal lakes lying west of the last-named, beside which I travelled on i 8th April 1895, the forests are very thick and luxuriant. The reason why the Tschöl-köl alone is destitute of forest would therefore appear probably to be this, that during certain periods the lake has dried up, for example when the Jarkent-darja flowed along the bed of the Kodajdarja. At that period the lake, contrary to its northern neighbours, lay at too great a distance from the river for its vegetation to be able to survive the interval of drought. Now neither this, nor anything similar to it, can have happened in the case of the Kara-koschun; for since its formation in 174o this lake has never been perfectly dry.
With regard to the second part of the passage I have quoted last from Kosloff, the statements he there makes are not quite correct. There have of course been periods in which the eastern waterway (Ilek) has gradually dried up, while at the same time the western (Tarim) has proportionally increased. But that has only been one phase in a process of unceasing oscillation; for a comparison of my observations of 1896 with those I made in i900 proves that, when the eastern waterway increases in volume, the Tarim diminishes. The account I have given of the Tarim in the first volume of the present work shows how unstable its hydrographical system is as a whole.
Kosloff gathers to a head his criticism of my former comments in the following words: »From all I have said above it follows that the observations made by Sven Hedin are to be explained in a different way: the desolate region lying east of the lakes which he discovered was formed, not by the Lop-nor, for it lay a full degree farther south, but by the Kontsche-darja in its uninterrupted effort to flow towards
Hedin, Tourney in Central Asia. II. 39
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