342 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



far no experiments have been made with the view to ascertain which of 

 the algae forming the " water-bloom" exercise an injurious influence on 

 fish. It is, therefore, very desirable that careful observation should be 

 made in this resjject. 



The SaprolcgniecB, a low variety of fungus, which are injurious to fish 

 eggs, are also frequently found in ponds on full-grown fish. They prob- 

 ably adhere only to sore places on the fish, and, spreading more and 

 more, frequently cover large portions of the body of the fish with a 

 thick slimy cover of a whitish color. This disease has been especially 

 noticed in fish kept in small basins, and often destroys a great many 

 fish ; but even when in a state of freedom in open waters fish are fre- 

 quently^ attacked by this epidemic, and in the English rivers the salmon 

 frequently die of this disease by thousands. The purer and cooler the 

 water is, and the more air it contains, the less will it favor the growth 

 of these fungi. A healthy vegetation of green aquatic plants prevents 

 their spreading all over a i^ond. 



Fish which have been attacked by these fungi may be cured, unless 

 very large portions of the body have become affected, by placing them 

 for a short while in a solution of water and 1 per cent of salt, or by 

 rubbing the sore places with a solution of water containing a higher 

 percentage of salt. 



As enemies of pond culture we may finally mention various diseases, 

 which are known by a variety of names, but of whose causes and nature 

 we are as yet almost entirely ignorant, and in respect to which we need 

 much accurate and painstaking observation. 



KoNiGSBERG, Geemany, July, 1885. 



10S.—Fl!^nERV INDUSTRIES OF TBE ISIiAIV]> OF OOKKAIDO, JAPAN. 



By K. ITO. 



INTRODUCTORY REMARKS. 



The island of Hokkaido, in Japan, formerly known as Yesso, is situ- 

 ated immediately north of Niphon or Hondo, and separated from it by 

 the Strait of Tsugaru. It lies between latitude 41° 21' and 45^ 30' 

 north, and has an area of 5,109 square ris (1 ri=2.5 miles). This island 

 has remained, for a long time, as a wild territory, roamed over by Aiuos, 

 an aboriginal race; and it is not more than twenty years since the 

 Japanese Government took up the effort for its colonization. 



The only industry carried on by Japanese in this 'island previous 

 to that time was fishing; and even in present days this constitutes 

 one of the most important industries of the island. It is, however, to 

 be remarked that the fisheries are confined to in-shoro work, and tlKi 

 method pursued in curing fish caught is yet very primitive. Hitherto 



