92 
IOWA ACADEMY OF SCIENCE Voi.. XXVII, 1920 
be a knowledge of the animals and plants present, with informa- 
tion as to their numbers, seasonal changes, and distribution. 
Gradually as these facts are assembled certain relationships may 
be made out. Obviously the question of main interest and im- 
portance is the bearing of all this upon the fish. It is hoped that 
the Laboratory, preferably in cooperation with state and national 
agencies, may contribute something toward this problem. 
As a part of the program there was carried out in the summer 
of 1919 a general survey of the larger plants of Lake Okoboji. 
The beginning of the work was delayed until the vegetation had 
reached full development for that year. During August a group 
of three workers from the Laboratory surveyed the shore zone 
of this lake, recording the kinds, relative abundance, and distribu- 
tion of the submersed seed plants. No account was taken of the 
vegetation of cut off ponds or bordering swamps, as the study was 
limited to the plants of the lake proper. 
Nearly two hundred stations were established on the borders 
of Lake Okoboji and cross sections were surveyed out at right 
angles to the margin until the water became too deep for larger 
plants. Dredgings along these lines were made with a many 
pronged hook, and depth measurements were taken with a weight- 
ed line. This survey was made possible largely through the 
courtesy of Mr. W. E. Albert, State Fish and Game Warden, who 
kindly loaned the Laboratory a small motor-boat for the work. 
The location of the boat was determined in part by estimating 
distances and also by sighting across headlands, etc., to known 
points on other parts of the shore and subsequently by use of 
map to plot in the points of observation. Owing to periods of 
windy weather it was not possible to study all parts with equal 
care. While the exact location could not always be known, es- 
pecially on rough water, the results are sufficiently accurate to 
outline the submersed vegetation, the extent of the beds, and 
certain relations to depth, bottom, and shore configurations. A 
chart showing the results of this general survey has been pre- 
pared; it may be useful as a guide in the more intensive study 
of the various parts and also of the lake as a whole. The map 
accompanying this article, prepared from these data, is much 
simplified as it shows only the total areas occupied by the larger 
plants. It is very difficult to indicate on a small map the distri- 
bution of all the species. The portions filled in with small circles 
show the distribution of Cerataphyllum demersum. The dotted 
