Rickett—The Larger Aquatic Plants of Lake Mendota. 503 
they could be separated according to the species, weighed, and 
spread out to dry. 
Method of Collecting. The attached plants of the lake, of which 
all but two species are seed plants, are found in a strip along the 
shore varying from 100 to 1000 m. in width. The vegetation 
covers the bottom, in varying degrees of density, at depths up to 
about 6.5 m. in some places. The average limit of the plant zone 
is at a depth of about 5 m. In almost all places, growth is con¬ 
tinuous from this outer limit up to the shore. Near the water’s 
edge is a strip of Cladophora,. varying in width from 1 m. to 40 
m., extending around the lake in almost all places where there are 
rocks to which it may attach itself. 
As one follows the shore line around the lake, it is easy to di¬ 
vide it into stretches which differ in character as regards the na¬ 
ture of the banks and of the bottom. It is natural to expect that 
the vegetation should show corresponding differences in amount 
and character, and such is found to be the case. Collections were 
therefore made on this basis, the distinctive regions referred to 
being designated as stations, of which there were 41. A station 
in general represents a region of fairly uniform physical and 
floral characteristics. It was originally intended to make collec¬ 
tions from all these stations, but, owing chiefly to unfavorable 
weather, the time was too limited to accomplish this end, and 
several stations were omitted. The number of stations (35) from 
which samples were obtained, however, includes every type of 
growth found in the lake. The shallow water was worked over 
first, enough samples being obtained in each station to represent 
every type of growth found within that station. Later, descents 
were made in deeper water in as many stations as possible. It 
soon became evident that, although there is no definite zonation 
of plants in regard to the distribution of certain species, the char¬ 
acter of the vegetation differs as a whole at different depths; i. e., 
certain species are found to predominate at certain depths which 
are not abundant at other depths. This fact has formed the basis 
for subsequent handling of the data. 
Keferenee may be made to the accompanying map for the iden¬ 
tification of the various stations, the width of the plant zone at 
various points, and the general character of each station. The 
designation of the limits of the plant zone is reproduced without 
change from Denniston’s map (preceding paper, fig. 1). Wherever 
this was checked it was found to be accurate. 
