60 American Fisheries Society 



a very conspicuous feature in the living egg. The eggs 

 of the herring and the skulpin exhibit a large number 

 of such globules, but have no floating power. 



Chemistry of Yolk-Color. 



The real nature of this red-colored material apart from 

 Miescher's and Hoppe-Seyler's early studies has never 

 been chemically determined thoroughly.* We know that 

 in the orange vitelline globe of the hen's egg (the yellow 

 yolk-ball) 11% or 12% consists of a lipoid, which the 

 best authorities regard as lecithin ; but some recent work- 

 ers, amongst them Dr. A. Erlandsen, have disputed this, 

 and tried to isolate cuorin from the yellow yolk, but did 

 not succeed. Serons and Palozzi, in further researches, 

 emphasized again the presence of the characteristic 

 lipoid, lecthin ; though the yellow pigment itself is a xan- 

 thophyll, really regarded by Willstatter and Escher as 

 an animal pigment called carotin-lutein, or lutein with a 

 carotin-like pigment in its substance. 



Practical Bearing on Fish-Culture. 



The answer to the question "Why are Salmon and 

 Trout Red-Meated?" would therefore seem to be, that it 

 is an hereditary feature, due almost certainly to the col- 

 ored material in the yolk of the egg from which the fish 

 developed. This colored material is unessential; it per- 

 sists as "oil drops" until a late stage in the early life of 

 the fish and is not used up, as the other contents of the 

 egg are; but finally it passes into the body-tissues, and 

 is found in the form of very minute bright red bodies, 

 seated in the cement substance of the individual fibrillse 

 of the great lateral muscles. That these colored bodies 

 are absent in some trout and salmon, and present in 

 others of the same species, demonstrates that they are 





*Miescher's researches are incomplete and inconclusive, and further 

 studies are urgent. Miss Newbigin surmised (op. cit., p. 161), that the 

 red color was a lipochrome pigment allied to tetronerythrin or zoonery- 

 thrin, and in the salmon is important in coloring the ova .... In the 

 male salmon the pigment is probably eliminated as the fat is used up, 

 (vide, p. 164). 



