75 



ous stones makes the soil still more unfavourable to vege- 

 tation because the stones retard the absorption of water, 

 reduce the capillarity and promote the conduction of heat in 

 the soil. On the other hand they act favourably by reducing 

 the evaporation from the surface (RAMANN). 



The vegetation will only be described for the more im- 

 portant localities I have seen (all with one exception in 

 summer). 



At the base of Sultan Uis Dagh, an isolated group of 

 mountains near Chiwa (see map), I examined a desert strewn 

 with loose pieces of slate, and dotted here and there with 

 rocks in situ. This desert evidently corresponds to what 

 VOLKENS calls "Kieselwiiste" WALTHER and MIDDENDORFF call 

 "Kieswiiste". As in Egypt, so the desert here was almost 

 devoid of plants. Only in depressions and where the number 

 of stones seemed to be less, did various low undershrubs and 

 dwarf -bushes occur: Salsola rigida, Artemisia herba alba, 

 Capparis spinosa, Atraphaxis compacta and Haloxylon Am- 

 modendron, the latter being low shrubs about half a metre 

 high. Less conspicuous were Stellera Lessertii, Convolvulus 

 fruticosuSj along with Halimocnemis macranthera and Anabasis 

 eriopoda, two pronounced halophytes. In Ferghana, MIDDEN- 

 DORFF found about one plant per square foot (1. c. p. 21) on 

 the stone-desert. 



The mountain itself, Sultan Uis Dagh (Sultan Baba-ne 

 Dagh-e) consists of nearly vertical strata of a greenish clay- 

 mica-slate, often impregnated with quartz. The surface in 

 many places is covered by disintegrated matter, fine yellow 

 clay and pieces of slate with a shiny tawny weathered sur- 

 face. Everywhere was very dry, even the deserted beds of 

 several streams, which were no richer in vegetation than the 

 rest. The following plants were found scattered widely about: 

 Atraphaxis compacta, Salsola Arbuscula, Salsola rigida, Cap- 

 paris spinosa, Artemisia sp., all dwarf or undershrubs, also 

 two withered annuals, a Composite and Lepidium persicum (?) 

 and low trees of Saxaul less than a metre high. 



At Kis-Kala, a mountain with a ruined castle, on the 

 right bank of the Amu Darya more to the south, I saw a 

 desert where the soil consisted of very stony gravel and sand. 



