60 The Natural History of the Salmon. 



ever is known of their further propagation and 

 progeny. 



" 2. Siebold has shown that some individuals of 

 every species are not sexually developed, and that 

 such individuals differ also externally from those 

 normally developed. However, 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 pecu- 

 liarities also remain permanent throughout life. 

 According to Widegren, this sterility is merely a 

 temporary immaturity, and a part of the individuals 

 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 ex- 

 ceeding the usual size of the species), are barren. 

 Externally they retain the normal specific charac- 

 ters. 



"The Salmon offers a most remarkable instance of 

 irregularity as regards the age at which the indivi- 

 duals 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 

 seven to eight inches long have their sexual organs 

 fully developed, and that their milt has all the 



