74 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



sugar, sets up fermentatioD, and gives rise to by-products (alcohol and 

 carbonic acid), so bacteria, by breaking up the muscles of the fish, &c., 

 set up putrefaction, and lead to the formation of by-products — some- 

 times harmless, sometimes extremely poisonous. With the organisms 

 of putrefaction surgeons and food-preservers have long waged war. 

 The surgeon at last has won the victory by means of Lister's anti- 

 septic system ; the food-preserver, guided by the discoveries of Pasteur 

 and Lister, has also been successful to a very large extent. In some 

 cases, after arresting putrefaction by boiling, he prevents the germ- 

 laden air entering by hermetically sealing ; in other cases he arrests 

 putrefaction by the use of ice. How may we further extend antisep- 

 tics to the preservation of fish ? A surgeon, in order to render a wound 

 aseptic, first endeavors to destroy all the organisms that exist in the 

 disintegrated tissues, and then does his best to prevent the entrance of 

 new organisms or their germs from the atmosphere. The antiseptic 

 fi*^h-preserver must, as far as possible, proceed on the same principle ; 

 he must get rid of the organisms that exist in and on the fish when it 

 reaches his hands, and either render the tissues unfit for the grov/th of 

 II new crop of organisms, or prevent the organisms reaching the tissues. 

 For hundreds of years tish-curers have endeavored to render the tis- 

 sues of fish unsuitable for the growth of organisms by saturating them 

 with salt. Those acquainted with the ])rocess adopted for the curing 

 of herring know how primitive it is. Not only is the flesh rendered less 

 nutritive, but the delicious flavor of the fresh fish is completely lost, 

 and the delicate albumens are decomposed. So much is this the case 

 that there is practically no sale for salted herring in this country ; they 

 are in demand only on the Continent, where fresh fish are scarcely 

 known. When lecturing at Fraserburgh last winter I directed the at- 

 tention of the curers there to a process of curing herring invented some 

 years ago by Mr. Sahlstrom. Mr. Sahlstrom's process, first tested in 

 Norway, has been recently carried out in Aberdeen. It consists first 

 in driving out the air from the newly -caught fish, and next in saturat- 

 ing the tissues with a preservative solution. The fish are introduced 

 into a closed cylinder, and there subjected to a pressure sufticieut to 

 drive out the air. Into this cylinder the preservative solution is then 

 introduced, and, by applying a pressure of from GO to 100 pounds to 

 the square inch, it is forced into all the tissues. The fish can be either 

 slightly or completely salted, and either pure salt or a mixture of salt 

 and boracic acid can be used. This method requires fewer hours for 

 curing herring than the ordinary method requires weeks, and, owing to 

 the tissues being thoroughly i)enetrated by the preserving fluid, they 

 are rendere<l quite incapable of forming a suitable soil for the growth 

 of organisms. Herring cured in this way can be exposed to the air for 

 weeks without deteriorating in value or losing their original flavor and 

 freshness. Another way of treating fish antiseptically is by Roosen's 

 method. This plan is at present under trial here for the preservation 



