The Species of the Genus Larix. 65 
of the rivers, where it is protected, and where the soil is 
fresher, it may develop better; in the extreme north, 
however, where it occurs on the forest-line, only stunted 
individuals are met with (Mıppr. |. c.; GOREDKOv, 1926, 
Ref. in Bot. Centralbl. XX, 1927, p. 246). 
In northern European Russia, the larch does not reach 
the forest-line, which chiefly consists of Picea obovata, but 
the situation changes as it approaches the Urals, where it 
becomes the only tree among the forest outposts, and this 
continues to be the case farther east (RıkLı in Vierteljahrs- 
schrift, Nat. Gesell. Zürich, XLIX, 1904, p. 132; vide CAJAN- 
DER, 1903). 
The tree is of common occurrence and one of value 
in the entire southern area; it is seen at its best in the 
Urals and the mountains towards the south-east in the 
western part of Altai. Krassnorr (1886, Ref. in Engl. Bot. 
Jahrb. IX, 1888, pp. 53—67) has investigated the occurrence 
of the larch in the western part of Altai, and particularly 
discussed the problem of its natural regeneration, which only 
takes place with difficulty in these regions. Further towards 
the east in Altai, in Tannu-ola, and other portions of the 
extreme north-west of Mongolia, its occurrence has been 
described by Price & Simpson (l. c. pp. 391 - 398). The 
best and most recent description of the West-Siberian Larch 
in its natural surroundings is PRINTZ's detailed account of 
its occurrence and development in Tannu-ola and the 
Sajan Mountains and the adjacent steppes. The area is an 
interesting one, the larch being described in all its forms, 
from the highest development in the fertile, fresh mountain- 
soil, to its isolated, decrepit appearance on the steppes. 
Under the most favourable circumstances, it may 
attain a height of over 40 m. with a diameter of about 
Vidensk. Selsk. Biol. Medd. IX, 2. 5 
