374 SCIENCE PROGRESS. 



organisms. The acid present is organic in nature, and 

 hydrochloric acid is absent. The number of bacteria in the 

 tract is very great, especially during the warm summer 

 months ; this fact is opposed to Miescher's idea that putre- 

 faction does not occur so readily in the upper water fish as 

 in those from the estuaries. The increase in organisms is 

 probably due to the diminished acidity of the gastric con- 

 tents. 



In making the observations bearing on metabolism, Dr. 

 Paton is himself principally responsible, though some of 

 the details were left to his colleagues, Dr. J. C. Dunlop, 

 Mr. Mahalanobis, Dr. F. D. Boyd and Dr. E. D. W. 

 Greig. 



Salmon were procured from the estuaries and from the 

 upper reaches of the three rivers, Helmsdale, Spey and 

 Dee, from May to November. It was not possible to say 

 when the fish captured in the upper waters in May and 

 June had left the sea, and it was considered fairest to limit 

 the investigation to a comparison of the upper water fish of 

 July and August onwards with the estuary fish from May 

 onwards. The whole fish in each case was available for 

 analysis ; in the muscles, separate analyses were made of 

 both " thick " and " thin" portions of the musculature, and 

 for tabular purposes, the figures are in all cases reduced to 

 a fish of standard length, viz., ioo cm., the length of a 

 salmon of about 30 lb. 



The tables of analyses given bear witness to the loss of 

 total solids in the muscles, and the gain in the weight of 

 ovaries or testes as the case might be. The large difference 

 between these two numbers gives the amount available as 

 a source of energy. 



Among the solids particular attention was directed first 

 to the fats, and secondly to the proteids. The fat stored 

 round the pyloric appendages and in the liver is also taken 

 into account. The numbers are much more complete with 

 regard to female fish than male fish, the number of male 

 fish available being too small for the drawing of satisfactory 

 averages. 



The changes in the muscle are described by Miescher- 



