PROCEEDINGS OF THE SOCIETY. 



289 



But although the plant life of Lautaret is thus vigorous and 

 exceptionally robust, it is no less remarkably varied, and 

 possesses many of the rarer species which occur on the 

 mountains running along the Italian frontiers. It is interest- 

 ing to find some of our own native plants intermixed with some 

 of the rarer forms of Southern Europe, both equally at home 

 in these highlands. 



Around the Hospice, and forming, no doubt, the basis of 

 the rich soil on which this luxuriant wild garden exists, are 

 jagged peaks rising up to 9,000 feet, composed almost entirely 

 of dark slaty rock. This substance lies on edge, and a constant 

 process of surface crumbling is goin^ on. Near the rocks the 

 material broken down is in larger pieces, but lower down 

 the slopes it gradually assumes finer division, until at last 

 it forms the rich basis of a soil deep, porous, and cool, in 

 which the plant world seems to luxuriate. To this fact is 

 attributable the extraordinary growth of this high-placed 

 flora. Farther afield, especially soutbwards, are ranges of 

 limestone rocks, which also give splendid results in their 

 meadows below, and have a distinctive bias in the variety of 

 their rock plants; while at other points granite rocks pre- 

 dominate, and there the flora gradually shrinks into compara- 

 tive smallness, both as to varieties and size. This variation 

 in soil material gives to the observer a very good demon- 

 stration of the important influence exercised by physical con- 

 ditions in the life-history of plants growing within large and 

 small areas. A striking feature of the district is the entire 

 absence of trees, the only representative being a shrubby Alder 

 which on some slopes forms dense masses that can scarcely be 

 penetrated. A very interesting method of botanizing the 

 district is to take in rotation the different levels and work 

 them apart. Thus, the lower prairie land, with its com- 

 paratively level and often swampy surface, yields a flora 

 completely different from that of the higher mountain slopes, 

 while the rocky peaks, in their varied construction, each afford 

 interesting species for examination. 



In the course of the paper, Dr. Brown referred to many of 

 the rarer and more interesting alpine plants which he had 

 observed in the district around Lautaret, and submitted for 



