1 84 LOCH CRERAN. 



which time the tide comes a good way up the stream 

 towards it, we observed a profusion of life in the fresh 

 water pool below, and great activity among a few small 

 trout that usually inhabit it. It turned out that these 

 were the little crustaceans (My sis), that so swarm in the 

 sea outside as well as in the brackish water, but this was 

 the first time we had observed them to have penetrated 

 to the pure fresh-water pools of the burn. Walking 

 further down, examining the teeming multitudes of large- 

 eyed, curved-backed creatures, we suddenly met a lively 

 party evidently in a most unaccustomed element. 

 Working assiduously, and with all its ciliae, fringing the 

 curtain, in active motion, a medusa was advancing up 

 the perfectly fresh water with apparently as much vigour 

 as if in the sea outside. Its every effort, too, was being 

 made to advance against the current up the stream, and 

 it must have been for some hours in nearly fresh water 

 ere we noticed it. It does not at all depend upon 

 simplicity of structure or low ness of organisation whether 

 a creature can endure the transfer from sea water to fresh, 

 and vice versa, as the starfish succumb at once to a fresh 

 water bath, which acts like a dose of prussic acid to these 

 simple organisms. On the other hand, the very beautiful, 

 intelligent, and highly-structured little gobies, even those 

 species taken in pure sea water, are apparently indifferent 

 as to the change ; and the same to an extent, and for a 

 time, may be said of the fifteen-spined stickleback, that 

 clever nest-building little fish that dodges you among the 

 more luxuriant seaware on a rocky shore. The simplest 

 way to procure these delightful objects for an aquarium 

 is one we have frequently made use of with success. A 

 little hand-net with a long handle is swept through the 

 sea-weed in a likely place, and if the spot is properly 



