Sunshine, Rain, and Wind 
vicar will represent. the dominant or master species 
found in all the best places.) But many cases are 
known in which one can change one sub-species into 
another, simply by transferring it to the other’s territory. 
Dr. Krasan found that Potentilla arenaria became P. 
viridis when planted on the sunny slopes where that 
species lived. The reverse experiment with P. viridis 
led to distinct changes in the direction of P. arenaria, 
but not to a complete transformation.” 
In Servia also three at least of the high alpine plants 
became common lowlanders when sown in the low- 
lands.* ~~ Soldanella alpina replaces S. montana in the 
higher alpine region, and many other cases might be 
quoted." 
The differences brought about by strong wind and 
a dry or sunny atmosphere are very marked indeed. 
Under such conditions the transpiration of water 
becomes extreme, and the skin or epidermis cells are 
especially affected. Their outer walls are reinforced 
by the deposit of more and more cellulose (probably 
due to the sacrifice of more protoplasmic elements for 
this purpose). This change is very well shown by our 
common bracken, which varies greatly according to the 
place in which it grows. In shade the leaves are thin 
and delicate, but in a dry exposed place they become 
thick and develop a special layer of thick walled cells 
(hypoderm). Indeed, by altering the outside conditions, 
one can leave half a leaf to become of the dry or sun 
type, and change the other half into the shade form by 
arranging some sort of shelter for it.?¢ 
There is a very interesting account of the “patanas”’ or 
upland district of Ceylon by Messrs. Parkin and Pearson.” 
* Trifolium orbelicum, Aster alpinus, and Alyssum repens became T, repens, 
A. amellus, and A. montanum, See also the interesting: division of the 
Geraniums according to climate and geography by Knuth.!5 
185 
