254 
NATURE 
[May 6, 1915 

PLANT LIFE IN ICELAND AND CYPRUS. 
(1) The Botany of Iceland. Edited by Dr. L. K. 
Rosenvinge and Dr. E. Warming. Part I. 2. 
An Account of the Physical Geography of Ice- 
land, with special reference to the Plant Life. 
By Prof. Th. Thoroddsen. Pp. 191-343. 
(Copenhagen: J. Frimodt; London: J. Whel- 
don and Co., 1914.) 
(2) Bergens Museums Skrifter. Ny Raekke. 
Bind i., No. 2. Studies on the Vegetation of 
Cyprus. Based upon Researches during the 
Spring and Summer, 1905. By Jens Holmboe. 
Pp. 344. (Bergen: John Griegs, 1914.) 
(1) HE present instalment of ‘The Botany 
of Iceland,” by Prof. Thoroddsen con- 
tains five chapters. The first chapter deals with 
general topography and geology. The island is a 
continuous table-land with an average height of 
700-1000 metres above sea-level, excepting narrow 
borders of coastal land, valleys which cut into 
the table-land on all sides, and a few small areas 
of level land towards the south and west. More 
than two-thirds of the entire area is at so great a 
height above sea-level that almost no vegetation 
can thrive there. The sandy and stony deserts of 
the interior plateau, the lava tracts, and the 
glaciers are not fit dwelling-places for man, and it 
is almost exclusively, therefore, the coasts and 
valleys which are inhabited. The volcanic element 
is the most striking feature in the geology, and is 
treated at some length. 
The second chapter deals with conditions of 
surface and soil. Basalt is the fundamental rock; 
the tuffs and breccias are for the most part basalt 
split and pulverised, and the mineralogical and 
chemical component is essentially the same 
throughout the island. The climate, discussed in 
chapter iii., is, owing to oceanic currents, much 
milder than would be expected from the position 
of the island. Evidence of the Gulf Stream is 
found in the drift material, which includes sugar- 
cane and seeds of Entada and other West Indian 
beans. The winter is long, but generally not 
severe; the summer is comparatively short and 
cold and the weather usually changeable and 
damp. 
The general distribution of plant life and a 
sketch of the chief plant-formations form the sub- 
jects of the remaining two chapters. Only a small 
part of Iceland bears a continuous carpet of vege- 
tation. The number of species of flowering plants 
and ferns is from 4oo to 450, as compared with 380 
in Greenland and about 1450in Denmark. Of these 
eighty-four are grasses and sedges. Man, with 
his sheep and cattle, has exercised considerable 
influence on the vegetation. The coppice woods 
of birch (Betula odorata) which were once exten- 
NO. 2375, VOL. 95] 


sive are rapidly disappearing, and their destruc- 
tion has affected the general vegetation. The 
nature of the country and the vegetation are well 
illustrated by a number of photographic figures. 
(2) The detailed study of the botany of Cyprus 
is the result of a desire on the part of a Nor- 
wegian botanist to compare with the flora of his 
own country that of an area in which there had 
been no glacial epoch. The author gives a brief 
sketch of the topography, geology, and climate 
of the island, and a short history of our know- 
ledge of the flora, including a list of plants men- 
tioned by authors before 1787. The main part 
of the volume is devoted to a carefully anno- 
tated systematic list of the vascular plants 
hitherto observed spontaneously growing in 
Cyprus, and some remarks on the most important 
plant-societies of the island. During his seven 
months’ stay the author was able to add consider- 
ably to the number of plants previously recorded, 
and also to study critically various elements of the 
flora. The cedar of the island he regards as a 
distinct endemic sub-species, with affinities partly 
with the cedar of Lebanon and partly with that 
of the Atlas range. Several new species of flower- 
ing plants are described, and these as well as 
many others of special interest are illustrated by 
excellent plates and text-figures. 
Large deposits of calcareous tufa were dis- 
covered containing excellent leaf-impressions con- 
sisting mainly of Laurus nobilis and Platanus 
orientalis, with fragments of Ficus carica, Smilax 
aspera, and Rhamnus oleoides, all of which are 
represented in the present-day flora. The account 
of the plant-societies, though not exhaustive, is a 
valuable contribution, greatly enhanced by a 
number of photographic reproductions. There 
are also short chapters on the means of distribu- 
tion of some of the plants and on the affinities and 
history of the flora; also a list of topographical 
names derived from plant names, and a biblio- 
graphy. 

PRIME NUMBERS AND THE COMPLEX 
VARIABLE. 
(1) List of Prime Numbers from 1 to 10,006,721. 
By D. N. Lehmer. Pp. xv+133. (Washing- 
ton, D.C.: Carnegie Institution of Washing- 
ton, 1914.) Price 5 dollars. 
(2) Functions of a Complex Variable. By Prof. J. 
Pierpont. Pp. xiv+583. (London: Ginn and 
Co., 1914.) Price 20s. net. 
(1) HE ttable is similar in form to Mr. 
Lehmer’s previously published factor- 
table (see Nature, August 10, 1911, p. 178), and 
the same elaborate precautions have been taken to 
avoid error. Thanks to the work of Glaisher and 


