PROGRESS IN BIOLOGICAL INQUIRIES, 1922. 17 



the dry body weight. About 18 per cent of the dry weight of the 

 body consisted of ash. 



The most important aquatic insects were larvae belonging to the 

 genera Chironomus, Tan}i;arsus, and Tanypus. A sample obtained 

 at a depth of 16 meters yielded a maximum of 8,200 larvae of these 

 three forms per square meter of bottom. Their combined weight 

 was equivalent to about 20 kilograms of dry material per hectare, 

 or about 18 pounds per acre. For the whole lake bottom the average , 

 number of these larvae was 1,148 individuals per square meter, yield- 

 ing a dry weight of about 5 kilograms per hectare, or 4.5 pounds per 

 acre. About 80 per cent of the live weight of these larvae consisted 

 of water and about 12 per cent of the dry weight was ash. 



BOTTOM FLOBA. 



Mr. Rickett made a quantitative survey of the larger aquatic 

 plants, similar to the study made by him on Lake Mendota. In 

 Green Lake the large aquatics extend out to a greater depth than 

 they do in Lake Mendota ; the extreme limit in the former is 9 to 10 

 meters and only 5 to 6 meters in the latter. The averages for the 

 various stations have not been computed yet, so that only a few of 

 the larger catches are indicated here. 



Chara was the most abundant form ; a sample taken at a depth of 

 1 meter yielded a maximum of 10 kilograms per square meter, wet 

 weight. Several other samples yielded as much as 8 to 9 kilograms 

 per square meter, but most of the samples contained only 1 to 3 

 kilograms of Chara, or less. About 82 per cent of the wet weight 

 of this plant consisted of water, so that a yield of 10 kilograms per 

 square meter would represent only 1.8 kilograms of dry material, 

 or 18,000 kilograms per hectare (16,000 pounds per acre). 



Ceratophyllum and Myriophyllum were found in great abundance 

 in some localities ; one sample taken at a depth of 4.5 meters yielded 

 7.8 kilograms of these two plants per square meter, wet weight, and 

 several other samples of corresponding magnitude were found. About 

 91 per cent of the wet weight of these two plants consisted of water, 

 so that the 7.8 kilograms above represented only 0.7 kilogram of 

 dry material per square meter, -or 7,000 kilograms per hectare (6,200 

 pounds per acre). 



The largest sample of Potamogeton consisted of Potamogeton am- 

 fUfolms. The wet weight of this sample was 2.4 kilograms per 

 square meter of bottom, of which 89 per cent consisted of water. 

 Vallisneria was next in rank with a maximum yield of 1 kilogram per 

 square meter, of which about 93 per cent wa-s water. 



INTERNATIONAL COMMITTEE ON MARINE FISHERY INVESTIGATIONS. 



The International Committee on Marine Fishery Investigations 

 held two meetings during the year — the first at Boston on November 

 4, 1921, attended by two representatives of Canada and two repre- 

 sentatives of the United States, and the second in Montreal on May 

 26, 1922, attended by all representatives of the United States and 

 Canada. On neither occasion was it possible for the representative 

 of Newfoundland to be present. This committee, while engaging in 

 no investigations on its own part, serves as a coordinating agency 



