172 Modern Fishculture in Fresh and Salt Water. 



Animals near together often refuse to breed or pro- 

 duce infertile progeny, called "mules" — for the term is 

 applied to all infertile hybrids, such as crosses between 

 the goldfinch and canary birds, and is not restricted to 

 the hybrid animal which serves our armies as neither of 

 its parents could do. The hybrid geese referred to are 

 "mules ;"' that term simply means an infertile hybrid. 



To question No. 2, I can only say that most of the 

 salmon family appear to produce fertile hybrids, as far 

 as the trouts and salmons are concerned, but no ex- 

 periments have been made to my knowledge with the 

 different whitefishes, smelts, etc., which "belong" to 

 the family by reason of some such slight affinity, such 

 as having the second dorsal fin composed of fat instead 

 of rays. 



To the third question I will say that I never knew 

 hybrid fishes to occur in nature. All animals prefer 

 to mate with their own kind. Nature abhors a mule, 

 and limits it to one life, with no progeny. I have 

 known a wild mallard to mate with a black duck and 

 raise a brood, but the birds were wounded and could 

 not fly, and they had no choice. This was on the Pa- 

 munky River, Virginia. Some men regard every ani- 

 mal which they are not acquainted with as a hybrid. 

 When the grayling was first brought to notice in Ameri- 

 ca, a man wrote to a sportsman's paper giving it as his 

 opinion that the grayling was a cross between a trout 

 and a sucker, and that man was a fish commissioner of 

 Illinois at the time. 



