378 
EXTRACTS FROM FOREIGN PERIODICALS. 
dicotyledonous plants in calcareous than in granitic mountains; on the most 
elevated points than in the centre of the Alpine zone (above the forests) ; lastly, 
in dry than in moist places. This last circumstance, already well known, ex¬ 
plains the two first, for calcareous mountains, and the tops of mountains, are 
liable to become very dry. In the granitic Alps of Glarus M. Heer found no 
Monocotyledon at a greater altitude than 9,000 feet. Between 7,000 and 8,000 
feet he found the proportion of one Monocotyledon to 5—Dicotyledons; from 
6,000 to 7,000 feet, 1:5^; from 5,500 to 6,000 feet, 1: 5 !^ At this last height, 
in a moist place, the proportion was 1:3^. On the calcareous Alps of the 
canton of Glarus the relative number of Monocotyledons is always a little smaller, 
or that of Dicotyledons somewhat greater, at equal heights; thus between 5,000 
and 6,000 feet the proportion is 1: 6. 
According to the Flora of Gaudin the proportion for the whole of Swisserland 
is as 1:3, 49. In the Alpine zone there are always fewest Monocotyledons. 
M. Heer has taken care to keep in mind the number ascertained, by many 
authors, for other chains of mountains, numbers which prove that the proportional 
diminution of Monocotyledons in high mountains, above the limits of forests, is 
a general law. 
The second article published by M. Heer is an account of the botanical geo¬ 
graphy of the canton of Glarus, very complete, and of great interest to individuals 
occupied in this branch of science. In the first part the author examines the 
physical conditions that influence the vegetation of the country; he describes 
the mountains and the vallies, makes meteorological observations on the tempera¬ 
ture and the quantity of rain in the several months of the year, and at various 
heights; lastly, he establishes the limit, so delicate, of the perpetual snows, 
the variable duration of the snow at different altitudes, and the climatic zones 
founded on all these facts. He next treats of the distribution of plants by 
stations, and in each zone. He enumerates the species and establishes the 
proportion of the families and classes in each of the zones. Unfortunately, the 
classification adopted by the author (that of M. Bartling), however excellent 
it may be in itself, has not been followed in the most important floras 
and works on botanical geography, and hence the numbers must be calcu¬ 
lated over again, in order to be compared with those of the principal authors on 
geographic Botany, for example with those of Brown, De Candolle, and De 
Humboldt. 
M. Heer has carried his investigations to the point of giving, for each zone, 
the relative abundance of species, and their greater or less disposition to grow in 
company or solitary. Proximate numbers indicate these facts in a very happy 
manner, although different from the plan adopted by M. d’Urville. The pro¬ 
cedure of M. Heer is to indicate by a numbep, from 1 to 10, the degree of 
