Muttkowski—The Fauna of Lake Mendota. 
375 
lecting. A square meter was laid out; the surface layer of 
the bottom and the fauna and flora within the area were gath¬ 
ered as completely as possible, placed in a sifting pan, the 
plants sorted over, and the whole sifted down to the compass 
of a liter jar (quart jar). Two to three stations,—that is, 
points, selected at random, each within one of the .fifty areas 
(see fig. 1) into which the lake was divided,-—were visited on 
a trip; the '‘hauls/’ each covering a square meter of bottom, 
were taken at successive depths. After all the jars were filled 
in the field, they were taken to the laboratory where the or¬ 
ganisms were sorted and counted while still alive and active; 
the sorting of "dead” collections offered too formidable diffi¬ 
culties to be attempted, for so many of the recognition char¬ 
acters of living specimens, such as position, method of locomo¬ 
tion, and color, are lost in dead material. 
Some reference seems appropriate as to methods of col¬ 
lection in the littoral area. In the shallower depths, up to 
three meters, the water of the lake was sufficiently transparent 
to permit accurate work. Beyond this collection was more 
difficult. To achieve a fair degree of accuracy a rake-net of 
25 cm. width was drawn over a strip of lake bottom, sufficient¬ 
ly long to make a square meter. This method was employed 
primarily in depths exceeding 3 meters. 
Investigations .—The main collections were made in spring, 
summer and fall of 1914 and 1915. During this time the“ lit¬ 
toral area of the lake was explored, both qualitatively and 
quantitatively; the aphytal area of the lake is now being 
studied from a quantitative standpoint. 
The work soon resolved itself into a series of phases: (1) 
A qualitative survey of the macrofauna; (2) A quantitative 
survey of the commoner macrofauna; (3) Ecological distribu¬ 
tion, and the criteria of lake life; (4) The breeding of un¬ 
known forms, and biological data on various species; (5) The 
actual use of insects as food by fish, and the reciprocal food 
relations of the fauna. 
With respect to the qualitative survey of the macrofauna, it 
was the original plan to consider only the insect fauna, but it 
soon proved desirable to include the remaining macrofauna, 
if only as a basis for comparison, and the quantitative meth¬ 
ods were extended to the other macrofauna, except fish. The 
lake was divided into 50 approximately equal divisions, or 
