5o6 POPULAR SCIENCE MONTHLY. 



are always in a well nourished condition. The intestines are surrounded 

 by masses of fat; the muscles in all parts of the body are full and 

 firm, and exhibit innumerable globules of oil within and between the 

 fibers. The sexes are practically indistinguishable. The genitalia 

 amount to only three-tenths of one per cent, of the weight of the 

 animals. During the months from May to December a gradual but 

 steady change takes place. The jaws of the males develop a beak 

 three to five centimeters in length. The skin of both sexes changes 

 color, losing much of its lustar, and becomes loose. The fat about the 

 intestines disappears first; then that contained in the muscles. Certain 

 muscles of the back, which are less important in swimming, diminish 

 to nearly half their original size; and their content of solids to an 

 even greater extent. The muscles most important in swimming, how- 

 ever, are maintained in full vigor; and even in those drawn upon, it 

 is significant that no loss of structure occurs; for on the salmon's 

 return to the sea, this material can be replaced without a recon- 

 struction of the tissue. Just before spawning, the average weight of 

 both sexes is ten per cent, less than that of fish of equal length 

 (eliminating the difference due to the growth of the jaws of the male) 

 caught in May. In contrast with these changes is the growth of the 

 genitalia. The testes or spermaries of the 'ripe' males amount to as 

 much as six per cent, of their body weight, and the ovaries or roe of 

 the females to twenty or even twenty-five per cent., and contain thirty 

 per cent, or more of the total solids of the fish. 



While the available information on the subject is as yet by no 

 means so complete as is desirable, on the whole it indicates that the 

 habits of the salmon in other parts of the world, and of other species, 

 are at least similar to those of the Rhine. It is the belief of many of 

 the guides in Maine and New Brunswick that the salmon in their 

 streams do not feed after leaving salt water, and that the *fly' 

 used to catch them must appeal to their curiosity rather than to their 

 appetite.* The salmon in the rivers of Scotland certainly resemble 



* During the past summer Dr. C. W. Green, of the University of Missouri, 

 has been carrying out investigations in conjunction with the U. S. Fish Com- 

 mission on the salmon of the rivers of the Pacific coast. As these researches 

 have not yet been publislied the writer is personally indebted to Dr. Green for 

 this statement : " Concerning the question whether or not the ' King ' salmon 

 takes food in its run up the Sacramento, I have reached the tentative conclusion 

 that it does not, in fact can not. Every salmon examined by me at the U. S. 

 Fish Hatchery at Baird, Cal., and I examined many, not only had no food in 

 the stomach and intestine bvit these organs were so much atrophied that only the 

 smallest object could have been swallowed. Salmon a meter in length have an 

 intestine not larger than a small lead pencil, and the stomach is reduced to less 

 than seven centimeters in length. On the other hand in the stomach of one 

 salmon taken direct from salt water at Monterey I counted eighteen squid and 

 several small fish." 



