PROFESSOR JOHN HUTTON BALFOUR. 61 
unproductive stony soil and displayed fertility only where 
moisture and the atmosphere had been able to pulverise the 
rocks. It is curious to notice the occurrence of species such as 
Oxytropis campestris and Lychnis alpina on single rocks in 
Britain. The latter we have already stated to be serpentine, and 
in the case of the former the rock appears in some respects to 
differ from those in its immediate vicinity, 
Luzula arcuata seems to prefer the granite in the district visited, 
and I have remarked the same thing in Sutherlandshire, where it 
is found on the granite of Foineven. 
Carex Vahlit grows on gneiss, C. leporina on granite, while 
Astragalus alpinus is common to both. Adsine rubella and 
Myosotis suaveolens occur on mica-slate. The ordinary alpine 
species appear to grow indifferently on granite, gneiss, and mica-_ 
slate. 
The range of species in the district will be illustrated by 
grouping species within divisions representing 1000 feet. us 
commencing at the sea at Aberdeen we have numerous sea- 
weeds, then Carer arenaria and incurva and the ordinary 
plants of the district, common trees, Goodyera repens, and 
Linnea borealis in the woods up the Dee. 
Reaching Castleton, Braemar, which is 1000 feet above the 
level of the sea, we come into a region where Genista anglica, 
Saxifraga atzoides, Alchemilla alpina begin. 
From 1000 to 3000 feet :— 
Thalictrum alpinum Erica cinerea 
Viola lutea Pyrola media 
Genista anglica »  secunda 
Rubus saxatilis as Melampyrum sylvaticum 
», Chamzemorus : Polygonum viviparum 
Alchemilla alpina Oxyria reniformis 
Saxifraga stellaris Listera cordata 
aizoides Tofieldia palustris 
Siti villosum Juncus triglumis 
Vaccinium Vitis-Idzea Lycopodium Selago 
Arbutus Uva-Ursi es clavatum 
Calluna vulgaris a selaginoides 
Erica Tetralix Beers aquilina 
. 2 
