of the Fisher II Board for Scotland. 11 



Excluding the gut, micro-organisms do not exist to any appreciable 

 extent in the tissues or body fluids of fish under normal conditions, 

 but after death the tissues offer comparatively little resistance to 

 the invasion of putrefactive organisms, which are soon found 

 multiplying in great numbers in the gut and all the body fluids, 

 gradually penetrating amongst the surrounding tissues. Among 

 the products of their activity are some substances of an alkaloidal 

 nature which are very poisonous and have recently been isolated 

 from decomposing fish ; one class, mytilotoxin, acts chiefly on the 

 nervous system, paralysing motor nerves like curara, while another 

 class affect the digestive organs, causing acute gastritis and 

 enteritis. It is thus a matter of importance to be able to detect 

 the earlier stages of decomposition in fish, which are sometimes 

 disguised. The criteria which Dr. Anderson considers in detail 

 are the general appearance of the fish, the firmness or softness of 

 the flesh, the appearance of the surface and scales of the eyes and 

 gills, the smell, the discolouration on the ventral aspect of the 

 backbone, rigor mortis, the manner in which the flesh strips away 

 from the backbone, and the appearance of the abdominal walls as 

 affected by the gut. 



Since it is possible to inhibit the action of most bacteria of 

 putrefaction by maintaining a low temperature of from 0° C. to 

 — 3° 0., while at the same time maintaining the fish in a condition 

 of rigor, fish may be preserved in a comparatively fresh condition 

 for a considerable time with very little deterioration in their 

 tissues, but at temperatures below — 3° C. they suffer considerably, 

 the muscles on thawing being very soft and limp, and such fish are 

 difficult to cure, have lost much of their natural flavour, and readily 

 undergo decomposition. As a result of experiments to determine 

 the Question as to the best time to ice fish, as on board trawlers, 

 whether before, after, or during rigor, Dr. Anderson found that 

 those which had been iced when rigor was completed were dis- 

 tinctly superior to those iced before rigor had set in or after it had 

 disappeared, the next best being those dealt with before rigor 

 supervened. The experiments were made on haddocks and whitings, 

 ungutted and gutted. It was found that rigor generally set in 

 earlier and disappeared earlier in trawled fish than in fish caught 

 by line, and since this allows of the earlier onset of decomposition, 

 it is concluded that the former are not equal to the latter either in 

 general condition, curing properties or keeping properties. The 

 author describes with technical detail the bacteriological part of 

 the investigation. 



The Specific Chakactees of the G'adid.e. 



In continuation of two previous papers on this subject. Dr. 

 Williamson contributes to the present Eeport a paper on the 

 specific characters of the haddock, whiting, and some other less 

 known members of the genus Gadus, together with a key to the 

 species of that genus which are found in northern waters. In a 

 group of fishes, as that of this genus, it is not possible to separate 

 the different members by a simple scheme, because the character 

 which may bs of value for separating two species may be quite 

 neutral in the other members. It is therefore necessary to take 



