SALMONID^. 639 



ever, he appears to have gone too far, when he stated that 

 this state of sterility extends over the whole existence of such 

 individuals, and that, therefore, the external peculiarities also 

 remain permanent throughout life. According to Widegren 

 this sterility is merely a temporary immaturity, and a part of 

 the individiials arrive at a full sexual development at a later 

 or much later period than others. To this we may add that 

 many Salmonoids cease to propagate their species after a 

 certain age, and that all so called overgrown individuals 

 (that is, specimens much exceeding the usual size of the 

 species) are barren. Externally they retain the normal 

 specific characters. 



The Salmon offers a most remarkable instance of irregu- 

 larity as regards the age at which the individuals arrive at 

 maturity. Shaw has demonstrated, in the most conclusive 

 manner, that those small Salmonoids, which are generally 

 called Parr, are the offspring of the Salmon, and that many 

 males, from 7 to 8 inches long, have their sexual organs fully 

 developed, and that their mUt has all the impregnating pro- 

 perties of the seminal fluid of a much older and larger fish. 

 That this Parr is not a distinct species — as has been again 

 maintained by Couch — is further proved by the circumstance 

 that these sexually mature Parr are absolutely identical in 

 their zoological characters with the immature Parr, which are 

 undoubtedly young Salmon, and that no Parr has ever been 

 found with mature ova. But whether these Parr produce 

 normal Salmon, impregnating the ova of female salmon, or 

 mingle with the Eiver-trout, or whether they continue to 

 grow and propagate their species as fully developed Salmon, 

 are questions which remain to be answered. We may only add 

 that, as far as we know, barren old Salmon are extremely scarce. 



3. The question ' whether any of the migratory species 

 can be retained by artificial means in fresh water, and finally 

 accommodate themselves to a permanent sojourn therein, 



