THE HEART OF THE ANTARCTIC 



tion of most of the animals suggests easy dispersal from 

 one to another. How are they conveyed? Only two 

 methods suggest themselves to one acquainted with the 

 local conditions. The skua gulls, which are so fond of 

 bathing, may transfer a few adhering to their feet when 

 they go from one lake to another. No other bird is at all 

 Hkely to assist in this process. The other method, which 

 seems likely to be the general one, is by wind. The weed 

 at the margins of the lakes gets exposed and dried by the 

 evaporation of the water, or more commonly by the abla- 

 tion of the ice from the surface. It is then very hght and 

 easily blown about by the wind, carrying its freight of 

 dormant rotifers, &c. 



The experiments detailed above show that in course 

 of this dispersal they are scarcely exposed to danger at 

 all. The hardest frost or the hottest sun cannot harm 

 them, and should they even fall into the sea, they will 

 not be killed if the plant which forms a raft for them 

 eventually reaches the shore, when they may be again 

 dried and driven by the wind till they find a suitable place 

 to resume living. A difficulty suggests itself in consid- 

 ing this theory of dispersal by wind. The prevalent wind- 

 storms are all from the southward. Northerly winds of 

 force enough to move the dried plants are almost unknown. 

 Though northerly winds prevail for a somewhat greater 

 number of hours during the year than the southerlies, 

 they are very light airs. Dispersal would then be easy 

 in one direction only, and might be very slow, and depend- 

 ent on the agency of the gulls in other directions. 



Life Among Moss 



The moss-dwellers are now well recognised among 

 microscopic animals. There are rotifers and water-bears 

 among the mosses at Cape Royds, but the mosses them- 



244 



