20 Part III. — Twenty -sixth Annual Report 



set up any exact standard of smell. The different terms used, such as 

 fresh, tainted, putrid, etc., can only have a relative value, although a 

 general standard is always understood. Still, it appears to me that it is 

 possible to place the more common edible fishes into two groups, the one 

 containing the haddock, whiting, turbot, halibut, plaice, and dabs, etc., 

 the other containing such as the salmon, eel, herring, etc. The members 

 of these two groups possess a very characteristic odour when removed 

 from sea water. The former may be described as fresh, fishy, and sea- 

 weedy ; the latter as fresh, fishy, but oily. 



The time taken before the fresh, fishy odour becomes tainted, stale, 

 and finally putrid depends, as already stated, on the degree in which the 

 media, the moisture, and the temperature are suited for the multiplication 

 of the bacteria of putrefaction. The processes follow along perfectly 

 definite lines, and are the same for all fish. 



In the case of washed, ungutted haddocks and whitings, experimented 

 with during last July and August, I invariably found the fresh, fishy 

 odour beginning to be tainted after 48 hours. With washed, gutted 

 haddocks and whitings a longer time elapses before the tainted odour 

 begins to be appreciable, but on an average it is marked at about 60 to 

 72 hours, and by 84 hours it is distinctly putrid. As regards herrings, 

 the time of appearance of tainted odour appears to be more variable ; 

 in some cases after 33 hours, in others not until about 50 hours, but, on 

 the whole, it is earlier than in the case of most white fish. 



9. Reddish Discoloration of Ventral Aspect of Backbonb. 



In all the fish examined, there appeared with striking regularity a 

 reddish-brown discoloration on the ventral aspect of the backbone, 

 usually between the second and third day in the case of line fish, and, on 

 the whole, earlier in the case of trawled fish. It is best seen in the 

 region extending from the kidney to the tail. The kidney itself is a 

 diffuse reddish organ, lying on the ventral aspect of the anterior region of 

 the backbone. It is very friable, and after death readily disintegrates to 

 form reddish debris in this region, but it is not to be confused with the 

 reddish discoloration round the vertebral column, which has a different 

 origin and a different significance. 



The earliest appearance of this thin red line in line-caught fish was 

 about 48 hours after capture. It gradually increases in size from |-inch 

 to |-inch in diameter during the following 12 hours, and is usually well 

 seen after 60 to 72 hours. Occasionally it was observed in trawled fish 

 before 48 hours after landing, and, on the whole, it appears earlier and 

 develops quicker than in line fish. 



The regularity of this appearance suggested a daily microscopic 

 examination of the blood in order to ascertain if there were any changes 

 taking place in it which in any way might be correlated with, and which 

 might be considered explanatory of, the reddish discoloration. 



Taken from the fresh fish, the red corpuscles are seen to be flat, 

 slightly bi-convex, oval bodies, with a reddish-yellow colour, showing 

 prominent nuclei and nucleoli. The white corpuscles show no special 

 feature. Occasionally a body will be seen which appears to contain 

 encysted sporozoa, and occasionally a slender, sometimes a thick, rod- 

 shaped bacillus-like body, or a few coccus-like bodies may be seen lying 

 in the serum. On the second day the red cells generally show a breaking- 

 up of their contents. The cell-wall in many cases shows dimpling and 

 creases, while in others the cell contents shrink away from the cell-wall, 

 leaving clear spaces, and a few bacilli may be seen in each field. On the 



