of the Salmon in Fresh Water. 5 



In drawing conclusions from the study of this material one question 

 must be considered. How far do fish captured in the upper waters 

 actually represent the condition of all the fish there ? These fish were 

 for the most part taken with the fly, and it is the common opinion of 

 anglers that fresh-run fish take the lure more readily than those which 

 have been in the water for some time. It is thus possible that the fish 

 procured from the upper waters do not fairly represent the general 

 condition. Fortunately at Kiiicraig, on the Spey, the fish were taken 

 with the net, and an examination of the various tables shows that they 

 do not differ from the fish taken with the rod in the upper reaches of 

 the other rivers. 



(/>) Preparation and Preservation of Matwial. 



The duty of examining and preparing the fish as they were received 

 in the Laboratory was discharged by Mr, Alfred Patterson, one of the 

 assistants, who had had a special training in analytic chemistry, and his 

 work was supervised by me. 



The external appearance of the fish was observed, and the presence of 

 sea lice, ulcers, wounds, &c., noted. 



The fish was then measured as follows : Length from mouth to fork 

 of tail, depth at anterior border of dorsal fin, and girth at the same 

 place. It was next weighed. The skin covering the trunk muscles on 

 one side was next carefully removed, along with the anal firi of that 

 side, any adherent flesh being afterwards carefully picked off and placed 

 along with the rest. The skin was weighed. 



The great trunk muscles on the same side were then carefully 

 separated from the bones, and weighed. In some cases the " thin " 

 belly muscle was separated from the " thick," and weighed separately. 

 It was soon found that the " thin " was about a quarter of the whole 

 muscle, and separate weighings were therefore discontinued. 



Pieces of the " thick " and of the " thin," of about 30 grms. each, taken 

 at the level of the anterior edge of the dorsal fin, were preserved in 

 spirit. Another portion of fie " thick " was weighed, and pounded up 

 with an equal quantity of common salt. 



The abdominal cavity was now opened, arid the viscera, with the 

 exception of the heart, the ovaries or testes, and the kidneys were 

 removed and weighed. The liver was separated from the other viscera, 

 and the condition of the gall bladder was noted. The gall bladder was 

 removed and the liver weighed. A weighed portion of the organ 

 about 30 grms. was put in methylated spirit. 



In many cases inoculations upon gelatin were made from the stomach, 

 pylorus, and intestine for the investigation of the bacteriology of the 

 alimentary tract. 



The stomach and intestine were opened, and the characters of the 

 contents noted. Small pieces of stomach, intestine, pyloric appendages, 

 and liver were in many cases placed in perchloride of mercury, and 

 pieces of the liver were sometimes fixed in osmic acid for microscopic 

 examination. 



The stomach and oesophagus were cut off from the lower part of the 

 alimentary canal, and were placed in alcohol. The pyloric appendages, 

 with the intestine, were placed in alcohol in a separate bottle. 



The ovaries or testes were now removed and weighed, the latter being 

 weighed without the ducts, which were cut off' close to the organs. 

 Pieces of the organs, of about 30 grms., were preserved in methylated 

 spirits. 



The rest of the fish, consisting of the head, heart, vertebral column, 

 kidneys, tail, fins, and the muscles of the other side, were weighed. 



