402 SECTIONAL TRANSACTIONS.—D. 
energies along these lines have been devoted to a study of Lake Nipigon, the 
first in the Great Lakes Chain. The lake is 1,752 square miles in area, with a 
maximum depth of 402 feet, and has been open to commercial fishing for the 
past eight years only. 
The central aim in the investigation has been to obtain data in regard to 
the natural annual production and its utilisation. To this end three main lines 
have been followed : (1) A study of the physical features such as the distribution 
of temperatures, oxygen, carbon dioxide, &c., and the relation of these factors 
to the fauna and flora; (2) the food supply for fish, involving qualitative and 
quantitative distributional studies of the plankton and the fauna of the bottom; 
(3) the fish themselves in regard to taxonomy, life histories, relative abundance, 
distribution, food, rates of growth, &c. 
The investigation has yielded much information in respect to the general 
ecological conditions existing in the lake and to economic questions such as 
competition for food among fish, rates of growth, correlations of age with 
length, weight, and girth, size of fish taken in nets of various sized meshes, and 
rate of mortality. In this connection special consideration has been given to 
such commercial fish as the common whitefish, the lake sturgeon, and the lake 
trout. 
23. Mr. W. J. K. Harxness.—Determination of the Rate of Growth 
and Age of Sexual Maturity in the Sturgeon (Acipenser rubi- 
cundus). 
The rate of growth of the sturgeon was determined by a study of the 
otoliths, and upon this basis the age of an individual can be estimated. From 
such data the following studies were made: The variation in the rate of growth 
of the fish at different ages, the changes that take place in external form at 
different periods of its life, and the age at which it becomes sexually mature. 
‘This last point is of particular significance to the sturgeon fisheries and in 
connection with artificial propagation. 
24. Prof. W. J. Daxin and Mrs. C. M. G. Daxin.—The Physiology 
of Nutrition in Aquatic Animals. 
The authors have continued their experiments with Axolotls, Goldfish, Plaice 
eggs, and Anodon. The oxygen consumption during various periods and under 
varying conditions of nutrition has been determined, and the rates of metabolism 
have been calculated therefrom. The results completely contradict those 
obtained by Pitter, which he set forth with his theory that the main source of 
nutrition of aquatic animals lies in dissolved organic compounds. The experi- 
ments bring out interesting relationships between the oxygen consumption, rate 
of metabolism, and the partial presence of oxygen, temperature, starvation, &c. 
25. Mrs. Karuneen F. Pinpney.—Acartia clausi var. hudsonica nov. 
var. A contribution towards the Correlation of the Pelagic 
Copepod Coastal Fauna of Northern Europe and North 
America. 
The two marine copepods Acartia clausi Giesbrecht and A. longiremis 
(Lilljeborg) have been found to be equally common off the southern and western 
coasts of Norway, where they are often taken together. A. longiremis, whose 
extra-Baltic range extends from the British Isles to the Polar Basin, is more 
neritic (inshore) in its occurrence, while A. clausi, which only exceptionally strays 
into the Arctic Circle, is more pelagic (offshore). Considering what we already 
know of the copepods of the Canadian plankton, it is not surprising to find that 
A. longiremis is constant in its more obvious characters on both sides of the 
North Atlantic, while A. clausi is not so identical with its old-world representa- 
tive, inasmuch as there is an absence of certain distinctive denticles on the 
edge of the last segment of the forebody. 
There is some evidence that A. longiremis may present local fluctuations in 
certain characters, but these do not seem sufficient to justify the introduction of 
varietal names for this species at present, 
