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. Heee 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, 

 J n 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 hi3 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 number, from 1 to 10, the degree of 



