How to obtain it. 251 



but they are to be carefully kept out of the stock ponds, which 

 are afterwards destined to produce fish in abundance for many 

 waters. 



In a state of nature trout often develop considerable de- 

 formities, and here we have the advantage, by careful selection, of 

 avoiding much of the risk of producing monstrosities and malfor- 

 mations, such as are found naturally in many localities. Cases 

 have been recorded of blind trout occurring extensively in some 

 natural waters, as for instance in the Fischau, near Mandorf, in 

 Germany. I have met with cases myself, both of total and partial 

 blindness, and instances have been recorded in which trout were 

 found to be blind in one eye only. Probably the last-mentioned 

 cases have been due to external causes, but I am satisfied that 

 instances of blindness occur amongst trout which are the result of 

 disease or hereditary weakness of some kind. Blindness is well 

 known to scientists to occur amongst other fish also. 



Deformities of the jaw and head are not uncommon in some 

 lakes, and, from experiments which I have carried out, I am 

 satisfied that in-breeding is one of the causes. Sometimes the 

 upper jaw is arrested in its growth, and becomes much shorter 

 than the lower one, whilst sometimes the lower one is similarly 

 affected. In some cases the lower jaw becomes so fixed that the fish 

 cannot close its mouth, and occasionally instances may be met 

 with in which the opercles or gill covers, instead of lying close, as 

 they should do, stand out at a considerable angle, and when fish 

 so affected are looked straight in the face, their faces have the 

 appearance of being surrounded by a sort of Elizabethan frill. 

 In the island of Islay is to be found a race of tailless trout, and the 

 hunchbacked trout of Plinlimmon, in Wales, have been alluded 

 to by many writers. These and some other deformities may be 

 caused by the fish being carried over waterfalls, as has been 

 suggested, but, on the other hand, there are many streams of the 

 same kind in which such cases do not occur. It is beyond 

 dispute that a fall from a height is liable to injure the spine of a 

 fish, and some crooked spines may be produced in this way. 

 This, however, would not account for the deformities of heads of 

 fish, and for the deficient gill-covers which have been found to exist. 



" Remarkable malformations are observed in the trout of 



