520 



matter of no little trouble and difficulty. Indeed, at first, such a catarrh 

 of the digestive tract suggested itself to me, but after proper precau- 

 tions were taken, I was at once convinced that no such thing existed. 

 It his, as I have already said, absolutely essential to cut open all parts 

 of the gut, including the pyloric appendages, and to place them in the 

 fixing fluid, immediately after capture at sea or at the river side. Dr. 

 G u Hand says, that in certain Berwick specimens fixed immediately 

 after death in sublimate, the conditions were the same as described 

 above by him. I cannot but think that in these cases there must have 

 been some slip in the preparations, or that there may have been some 

 little delay in fixing the specimens, for one has to remember that a 

 period of 30 minutes or even less is often quite sufficient to bring about 

 autodigestion in at least the pyloric appendages of the Salmon. 



Post-mortem digestion in the appendages and intestine is an alka- 

 line one, and is efiected by the action of the pancreatic secretion. In 

 trout autodigestion in these structures is comparatively slow. On one 

 occasion in the case of some trout taken from the river Dee which were 

 dying from the effects of alkalis issuing from a neighbouring paper 

 mill, I found that in a very short period after death — one to two hours 

 — the pyloric appendages had suffered post-mortem digestion to an 

 enormous extent, while that part of the body wall lying adjacent had 

 been eroded right through. The trout, as the contents of their sto- 

 machs showed, were feeding voraciously. Such an occurrence is not 

 found in ordinary healthy trout as every one knows, while it indicates 

 in some measure how a difference in the amount of alkali present can 

 alter the character of the digestive secretion. Because of the identity 

 of structure in the digestive canals of the salmon and the trout. Dr. 

 Gull and concludes that their functional properties are also identical. 

 It is quite true that for such reasons the functions in both may be the 

 same in kind, but is it so easy to determine identity in degree of 

 function ? 



But though there is no such thing as the occurrence of desqua- 

 mative catarrh in the gut of the salmon, there do exist certain changes 

 of importance. These I shall at present briefly refer to, a fuller descri- 

 ption being reserved for a future paper. 



In the stomach of the river salmon the epithelium undergoes 

 interesting changes in its character. The glandular layer is much re- 

 duced in thickness owing to the diminution in size of the component 

 cells. The deeper cells of the cardiac glands are smaller and more gra- 

 nular, while the more superficial cells and the cells of the pyloric glands 

 are also smaller and possess more shallow mucigen cups than those 

 in the sea salmon. As a consequence the lumen of the gastric gland 



