. 
“4 
.- 
20 
mological studies, mollusean collections and determinations, fresh-water 
worms, studies of Protozoa and Rotifera, chemical determinations, reports 
and publications, and the summer opening of the Station. 
PLANKTON OPERATIONS. 
The minute plant and animal life suspended in the waters of a river system, 
moving downwards with its current and washed to and fro by its waves, com- 
poses what is known to the modern biologist as the plankton of its waters. The 
Station operations in this field were primarily directed to a study of the amount — 
of this plankton in the various locations selected, its seasonal and other 
periodic changes, its local and vertical distribution, its composition as to'the 
species represented, and its relation in the general system of aquatic life. — 
Our field of operations is a unique one, as yet practically untouched by the — 
scientific investigator, in so far as it is hmited to a river system and its de- 
pendent waters. 
The plankton substations in 1894 and 1895 were five in number, one in the 
river, a short distance above the foot of Quiver Lake, another in Quiver Lake 
itself, a third in Dogfish Lake, a fourth in Thompson’s Lake, and a fifth in’ 
Flag Lake, between Thompson’s Lake and the river. To these were added in 
1896 a substation at Phelps Lake, from which, indeed, a single quantitative 
collection had been made in 1894, and another in Spoon River a short dis- 
tance above its mouth. From these various substations a thousand quantita- 
tive collections have been made since the Station opened, those from April, — 
1894, to June 30, 1895, by Professor Frank Smith or under his immediate — 
direction and those subsequent to that time by Dr. C. A. Kofoid.- All these — 
tows have of course been carefully preserved by methods such as to permit — 
their quantitative comparison and about three fourths of them have been — 
quantitatively determined by Dr. Kofoid by methods of precise measure- 
ment. A considerable beginning has also been made in the enumeration of — 
their contents by counting under the microscope. 
cy 
Various modifications of plankton methods, elaborate tests of the apparatus — 
used and of the methods of discussion current, and other items of improve-_ 
ment in the equipment and in the methods of planktology will be reported by — 
Dr. Kofoid in a paper on this department of our work now nearly ready for 
the press. For certain general conclusions of considerable interest and of at 
least provisional value reference may be made to the same paper. , 
COLLECTIONS ACCUMULATED. ie 
The total number of lots of specimens collected since the opening of the 
Station amounts to 6,628, besides 5,500 pinned insects. Of the former, 434_ 
lots contain materials for a study of the food of animals, 300 of them being 
the contents of the stomachs of fishes; 270 are specimens of vertebrates; 
3,560 are preserved collections of invertebrate animals; 1,823 are towing-net 
collections; and 543 were collections of Rotifera and Protozoa, most of whie 
were studied alive because incapable of satisfactory preservation. The entire 
