TROUT IN ISOLATED LOCHS 159 



visiting strangers among the many forms of impiety 

 generated in the South. And impious or not, 

 most of the explanations carry themselves with a 

 far-fetched air. Thus Darwin, referring to fresh- 

 water productions, says that " fishes still alive are 

 not very rarely dropped at distant points by whirl- 

 winds," and though the old stories of " showers 

 of frogs and fishes " are certainly not so mythical 

 as they were once esteemed, they strain credulity 

 when applied to the case of the thousands of hill 

 tarns. Another explanation is that the ova may 

 be carried from water to water adhering to the 

 legs of wading and swimming birds. As the ova 

 of fresh-water fish retain their vitality for a con- 

 siderable time after removal from the water, this 

 solution of the problem is not one to be instantly 

 rejected. It has been proved in the most con- 

 clusive fashion that water-fowl do frequently carry 

 with the mud adhering to their legs the seeds 

 of water-plants, and newly-hatched fresh-water 

 molluscs have been found adhering to their feet. 

 It is also suggested that water-fowl which eat 

 fish ova may carry some uncrushed on their beaks 

 from water to water. But these methods, with 

 their bare possibility, their dependence upon acci- 

 dent, are far from satisfying when applied to a 

 case in which so very many accidents are required. 

 A third solution offered by sober science repels by 

 its sheer stupendousness. The levels of the 

 country, we are reminded, were not always what 

 they are to-day. Streams which now run in deep 

 valleys have dug out those valleys for themselves, 

 and one which to-day runs a thousand feet below 



