242 TJ. S. BUEEAU OP FISHEKIES 



hausted in a very short time, while the carbon-dioxide content in- 

 creased rapidly. During most of the time the oxygen content ranged 

 from 0.24 to 0.56 part per million and the carbon-dioxide content 

 from 13 to 25 parts per million. 



Except for a short period immediately after the water was changed, 

 the fish swam at the surface continuously and sucked in air, which 

 passed out over the gills, enabling them to get oxj^gen from this source 

 rather than from the water. Inasmuch as the mortality in each lot 

 was low, it is evident that goldfish can live for some time under such 

 conditions. Toward the end of the experiment, the fish began to show 

 signs of low vitality, which evidently was due more to the accumula- 

 tion of excrement, m.ucus, and other wastes, than to a deficiency of 

 oxygen. From the experiment it appears that in ordinary commer- 

 cial shipments of goldfish the removal of waste matter from the cans 

 is more important than aeration. 



An investigation into the life history of Proteocephalus cmiblop- 

 litis, a cestode parasite of bass, was carried on by Dr. George W. Hun- 

 ter at the Neosho (Mo.) station. The larvae of this tapeworm some- 

 times occur in such numbers in the ovaries of the host as to prevent 

 effectually the development of the ova. Adult tapeworms are found 

 in the intestines of bass and allied species. It was found that tape- 

 worm eggs may develop in several species of Cyclops (a genus of 

 small crustacean common in the plankton of ponds). When ingested 

 by the proper species of Cyclops, the eggs hatch and the larvse bore 

 through the intestinal wall into the body cavity of their host. When 

 the infested Cyclops is eaten by a fingerling bass, the parasites encyst 

 in its body cavity or viscera, where they may remain for months or 

 possibly years. If infested bass are eaten by larger bass, the parasite 

 is carried to the intestine, where it completes its development. It is 

 probable that the larval stages of the parasite may occur in other 

 small fishes as well as bass. Doctor Hunter's studies have not been 

 completed but will be continued during the coming summer. 



STUDIES ON INTERIOR LAKES 



During the past several years the Bureau of Fisheries has been co- 

 operating with the Wisconsin Geological and Natural History Survey 

 in detailed and highly technical limnological studies of lakes in 

 northeastern Wisconsin, conducted by employees of the State. Their 

 purpose is the discovery of the real causes of unequal productivity of 

 the various lakes, with the hope of eventually being able to increase 

 the production of fish in lakes now depleted and to establish fish life 

 in waters now barren. Painstaking Investigation of the chemistry of 

 waters is just as necessary for promoting aquiculture as similar 

 studies on the chemistry of soils are in agriculture. Because of the 

 fundamental scientific importance of these studies and their far- 

 reaching ultimate application to aquiculture in inland waters, the 

 full report of activities submitted by Prof. Chancey Juday is given 

 below : 



During the summer of 1927 limnological studies on the lakes of northeastern 

 Wisconsin were continued. Laboratories were provided by the State conserva- 

 tion commission, which gave to the survey the use of two buildings at the 

 forestry headquarters on Trout Lalie. The first members of the field party went 

 to Trout Lake on June 17. About a week was needed to equip the buildings for 



