Investigations on the Life- History 



II. THE SOUECE FEOM WHICH SALMON OBTAIN 

 NOUEISHMENT AND THE EXCHANGE OF 

 MATEEIAL IN THE BODY DUEING THEER 

 SOJOUEN IN FEESH WATEE. 



A. THE POWER OF THE ALIMENTARY CANAL TO 

 DIGEST AND ABSORB FOOD. 



In regard to this question the following evidence is at present forth- 

 coming. Miescher Ruesch states (loc. cit.) that the stomach and gullet 

 of the fish taken at Basel, about 500 miles up the Rhine, were contracted 

 and folded, contrasting strongly with the distended stomach and gullet 

 of the salmon taken in the East and North Sea. The stomach and 

 intestine contain a clear slimy material which is never acid, while the 

 intestine and pyloric appendages contain a slimy pus-like material full 

 of shed epithelial cells. There was never any trace of auto-digestion. 

 The glycerin extract of the slimy matter on the addition of dilute 

 hydrochloric acid had sometimes a slightly dissolving action on fibrin, 

 but so slight that it was concluded that no true digestive secretion was 

 secreted. The gall bladder in all cases was collapsed, but the contents 

 of the intestine are described as having a more or less deeply bile- 

 coloured appearance. 



He further states that the intestines of these fish taken from the river 

 did not show the same tendency to early putrefaction as did the intestines 

 of sea salmon, and this, he thinks, was due to the fact that no food being 

 taken no organisms were introduced into the stomach. In his whole 

 series of nearly 2000 fish, he found evidences of feeding in the stomachs 

 of two only, both male kelts. In one the scales of some Cyprinoid fish 

 were found, in the other an acid secretion was contained in a distended 

 stomach, possibly indicating that digestion had been going on. 



From this evidence he concludes (p. 164) that "the Rhine salmon 

 from its ascent from the sea to its spawning, and also after this, as a 

 rule takes no nourishment." 



The investigation of the Scottish Fishery Board carried on at Berwick- 

 on-Tweed yielded results which are hardly comparable with those of 

 Miescher, inasmuch as the fish were here captured either while still in 

 the sea or just after leaving it. 



The question is not only one of very great interest, but it is of 

 prime importance as regards the further investigation of the changes 

 in muscles, ovaries, and testes. 



On considering Miescher's results it seemed to us desirable to repeat 

 some of his observations and to extend the scope of the enquiry. 

 With this purpose Dr. Gulland has studied the microscopic changes in 

 the digestive tract, while Dr. Gillespie has investigated the digestive 

 activity and the bacteriology of the stomach and intestine. 



