of the Fishery Board for Scotland. 



31 



APPENDIX F. — No. I. 



ON THE CHEMISTRY AND HISTOLOGY OF THE 

 DIGESTIVE ORGANS OF FISHES. 



By WILLIAM STIRLING, M.D., Sc.D., 



Regius Professor of the Institutes of Medicine in the University of Aberdeen, 

 With Plates I. and II. 



INTRODUCTION. 



Although the process of digestion in the alimentary canal of mammals 

 has heen studied with great care, it is remarkable that but few observa- 

 tions have been made upon the digestive processes in fishes, and more 

 especially upon our common food fishes. 



With the view of determining to what extent the process of digestion 

 in fishes resembles or differs from that in man and other animals, at the 

 request of the Scientific Investigation Committee of the Fishery Board 

 for Scotland, I undertook some investigations at the beginning of this 

 year upon some of our more common food fishes, such as the herring, 

 cod, haddock, and skate. The present Report is, however, to be regarded 

 merely as preliminary, as many difficulties stood in the way of giving 

 anything like a complete report on so wide a subject in so short a time. 

 The observations were commenced early in January, and were continued 

 as opportunity afforded until the beginning of May of this year. 



One of the first essentials to success in making chemical and micro- 

 scopical investigations is to have absolutely fresh material to work upon. 

 Now this was not always possible, as much of the fish which is landed 

 is ' trawled ' fish, which have been dead for many hours, and are there- 

 fore unsuitable for such delicate investigations. I had therefore to rely 

 chiefly upon material that had been caught a few hours before it was 

 subjected to examination. Another source of difficulty was that, owing 

 to the high winds that prevailed off our coast, fresh fish suitable for my 

 purpose were frequently not obtainable. 



As the quality of fish differs greatly at different seasons, and according 

 as the fish are or are not breeding, one would suppose that there would 

 also be differences in their digestive organs, and also in their food 

 under these different conditions. The fish I used were all caught off the 



