116 



The Naturalist. 



dispossessed by the influx of new species, except from places such as 

 barren sandy heaths and mountains, where their physiological consti- 

 tution gives them an advantage over the invaders. 



If we think of the plants that are common to lowland districts and 

 to mountains, we shall find that, with the exception of sturdy species 

 which can get a living anywhere {e.g, the daisy), the great majority 

 are plants which in the lowlands are found chiefly or only on sandy, 

 often wet heaths. As examples I may give Galium saxatile, Erica 

 tetralix, E. cinerea, Galluna vulgaris, Vaccininm Mgrtillus, Pinguicula 

 vulgaris, Narthecium ossifragum, Juncns squarrosus, Carex fiava, Aira 

 Jlexuosa, Nardus stricta, Molinia coeruUa, Nephrodium Oreopteris, the 

 Ijycopodia, the sundews, &c., with many mosses and lichens. The 

 conditions favourable to the plants which sandy heaths possess in 

 common with mountains, appear to be — plenty of fresh air ; an 

 atmosphere free from smoke and other impurities derived from human 

 habitations ; humidity ; and above all, the absence of undue compe- 

 tition of other plants, particularly of the grasses and others which 

 form the herbage of our pastures, and of the common weeds of 

 cultivated ground. A barren soil, and the cold of great elevations, 

 have a similar effect in preventing the growth of these competing 

 species. Cold favors arctic and alpine plants, not so much directly as 

 indirectly ; and it is not that they cannot grow without cold, but 

 that they can stand cold, and other plants can not. It is stated that 

 in Switzerland no plants are found above the snow-line which do not 

 also extend below it ; and, on the other hand, many alpine flowers 

 thrive well on our English rockworks, where the watchful eye of the 

 gardener protects them from the weeds which would otherwise spring 

 up and choke them. 



HINTS TO YOEKSHIRE ENTOMOLOGISTS. 



By S. L. Mosley. 



Now that our Union has placed us upon a firmer basis, I should like 

 every member to throw his hands right heartily into the work, and 

 let us see what the county is worth from a Natural History point of 

 view. There are a few things that require doing, which have been 

 neglected both here and in almost every other part of Britain. To 

 be brief, we want workers in Diptera. This is a much neglected 

 order, the probable cause being that there are so few workers that it 

 is difficult to get help, and the insects themselves are less gaudy and 



