18 U. S. BUREAU OF FISHERIES. 



decomposition. So in salt fish the fat is in the presence of moisture 

 and an abundance of enzyme, and the necessary warmth is usually 

 present also, ideal conditions for decomposition. The fat having 

 been split to fatty acid, there are two factors, so far as known — 

 namely, air and light — which promote oxidation. 



Some little study has been devoted to the effect of salts, such 

 as sodium chloride and calcium chloride, on the splitting of fats, 

 but not enough is known about the effect of these substances in con- 

 centration to be of any assistance. Whether or not bruises have the 

 effect in promoting decomposition of fat that they have in promot- 

 ing decomposition of protein is not known but would be well worth 

 knowing, and here further investigation is certain to be of value. It 

 is known that much of the fat in living fish is contained within in- 

 closed cells, and that even the fattest fish is not greasy when fresh. 

 But whenever the cells are ruptured by rough handling, decomposi- 

 tion or whatever cause, the oil escapes and is exposed to all the un- 

 favorable influences of enzymes, moisture, air, and light, and the 

 fish becomes greasy ; eventually it Avill become rancid. And, further, 

 oil escaped from the fish, being of a low^er specific gravity than 

 brine, at once rises to the top of the barrel and is lost as food. 



All sorts of possible preventives of rust are practiced or suggested 

 for practice — such things as impermeable barrels, air-proof covering 

 over the liquid, a reducing substance in the brine to absorb 

 the oxygen, cool, dark storage, and the like. There is, of course, 

 much dissolved oxygen in the juice of the fish and in the brine and 

 also considerable amounts of free oxygen occluded in the cavities 

 of the fish to effect considerable rancidity, even if all outside air is 

 excluded. This dissolved and occluded air can be removed by a 

 vacuum pump, but this has never been tried commercially, so far as 

 the writer is aware. Very little improvement can be expected until 

 the problem has been thoroughly investigated by scientific methods. 

 In the improved technique recommended .by the Bureau of Fisheries 

 in Florida complete covering of the salt fish by brine in tight barrels 

 was specified. 



REDDENING OF COD AND HADDOCK. 



If cod and haddock escape rusting because of lack of fat, they 

 are subject to another enemy perhaps as bad, namely, reddening, by 

 which large quantities of cod and haddock are lost every year. For 

 the past three years work has been conducted by the division of 

 scientific inquiry of the Bureau of Fisheries on the causes of redden- 

 ing and significant results have been obtained. The cause, in gen- 

 eral, has been known for many years to be bacteria, but otherwise 

 little has been known of the origin of these bacteria or of their 

 peculiarities. 



Briefly stated, the results of the work cited are as follows: The 

 bacteria that cause reddening are of two distinct kinds — a spirochaete, 

 which in colonies is pale pink, and a bacillus whose colonies are deep 

 red. The two organisms grow in such close harmony that mixed 

 colonies occur which vary in color from pale pink to deep crimson 

 as the proportions of the two organisms present vary. The evidence 

 points to the solor sea salts from the tropical and subtropical seas 

 as the source of the infection. Solar sea salts, both American and 

 foreign, are infected. Mined salts seem to be free from the infection. 



