id — 
dent upon the climate and not upon the soil, and that its 
surface in many places consists of impermeable clay, the 
reasoning Of GRISEBACH has a great amount of truth. Kos- 
TYTSCHEFF, ISMAILSKY and Krassnow independently point out 
the same circumstance in the Russian steppes, that the ab- 
sence of tree-growth (among other things) is caused by tbe 
surface layer of the soil not permitting the water to penetrate 
into the depths. With reference to Transcaspia, ROMANOWSKI 
states (p. 56) that in layers of gravel under the loess, water 
is found and is widely diffused under the soil. This may be 
rain or snow absorbed through sand’), or it may originate 
from rivers which have sunk into the sand. “Consequently 
the sand-steppes of Turan cannot be said to be absolutely 
waterless.” 
Here then we have probably the reason — or one of the 
reasons — why the desert has trees, the steppe none. The 
presence or absence of trees taken along with the relation of 
the water to the soil, seem to me so important, that they, 
together with the climatic conditions and the conditions of 
the soils, must be regarded as distinguishing characters be- 
tween steppe and desert. 
For my own part I regard the steppe (grass-steppe) as 
mainly a closed plant-formation (or group of formations) oc- 
curring on soil rich in humus without excess of sulphates 
and chlorides, and with a comparatively moist surface-soil; 
the vegetation consists of herbaceous perennials, undershrubs 
and annuals while trees and bushes are wanting. 
The soil of the desert, on the contrary, is devoid of 
humus or very poor in humus, and contains many sulphates 
and chlorides. The subsoil is (always?) better supplied with 
water than the surface. The formations are very open and 
they frequently include trees and bushes. 
This attempt to explain the terms steppe and desert may not 
lead to any sharp distinction between the two, so much the less 
1) In this connection it may be pointed out that the steppes of 
southern Russia have their maximum precipitation in summer so that the 
water will evaporate quicker than in Transcaspia where maximum occurs 
between winter and spring. OP: 
4 
