376 SCIENCE PROGRESS. 



up to August, the proportion is i : 1 1 ■ 6. Sufficient male 

 fish in the later months were not obtainable. 



In connection with phosphorus, the results indicate that 

 the phosphorus stored in the muscles as simple phosphates 

 is transferred to the ovaries and testes, and there built up 

 into organic combinations. In both glands, lecithin ap- 

 pears to occupy an important step in this conversion ; but 

 while in the testes the change to the true nucleins is carried 

 out at once, in the ovum an intermediate product ichthulin 

 (a pseudo-nuclein) is first formed, and undergoes the change 

 into nuclein as the embryo develops. 



The gain of iron which occurs in the ovaries is not 

 derived from the muscles nor from the liver. In all pro- 

 bability its source is therefore the haemoglobin of the blood. 



The last point I shall mention is that relating to the pig- 

 ments, which were investigated by Miss M. I. Newbigin, 

 who is already well known from her work on Crustacean 

 pigments. The colour of salmon flesh is due to two lipo- 

 chromes, one being the widely distributed yellow pigment 

 lutein, the other a bright red pigment closely resembling 

 that occurring in the Crustacea. 



The same pigments are found in the ovaries, and as the 

 season advances the red colouring matter accumulates in 

 the ovaries and disappears from the muscles. The red lipo- 

 chrome probably originates from the yellow, and the latter 

 is probably derived from the herring, etc., on which the 

 salmon feeds. The purpose which the pigment seems to 

 serve is to assist in concealing the ova when they are shed. 



The main conclusions to which the report points are the 

 following : First, that when the fish enters the river it 

 ceases to feed, and has to rely entirely on its own re- 

 sources, namely, the materials stored in its muscular tissue. 

 The evidence on which this rests is much more conclusive 

 than in Miescher's earlier investigations ; though perhaps 

 the sceptical fisherman may still ask, Why, then, does the 

 salmon rise to the fly ? 



Secondly, of the stored material by far the larger fraction 

 is used for the development of kinetic energy ; this is 

 especially true for the fats, particularly in the latter portion 



