Li 
lections so made have been worked out in a way to give the 
actual quantity of organic life in a cubic meter of water for 
each situation studied by this method, and enumerations of 
various forms have likewise been made under the microscope by 
methods such as to give us reliable data for a comparison of the 
various waters with reference to the number of such forms in a 
cubic meter of water. Approximately quantitative collections 
have likewise been made, wherever possible, in situations which 
do not permit the use of this plankton apparatus, but with 
results far less reliable, of course, because based mainly on per¬ 
sonal estimates, and obtained by the use of less precise and 
exhaustive methods. 
It seems not impossible that quantitative and numerical 
plankton work will be found to have a certain value as a ground 
of inference concerning the biological contents of water which 
cannot be searched by the plankton apparatus. In other words, 
definite, if general, relationships may be found to exist between 
the amount and composition of the plankton in the free and 
open water of a given lake or stream at any given time and the 
mass and variety of living forms contained in the marginal shal¬ 
lows or imbedded in the mud of the bottom. 
Considerable modifications have been made at the Station 
since it opened, in the details of the quantitative method, often 
forced upon us by the peculiarities of the location and the 
special conditions under which our work was carried on, and 
interesting improvements in special apparatus have resulted 
from the effort to overcome our peculiar difficulties. A paper 
on our plankton methods and apparatus is now in course of 
preparation by the Superintendent of the Station, Dr. C. A. 
Kofoid, to whom this department of the work has been assigned. 
As our work progresses and special problems are taken up 
for separate and continuous investigation, the experimental 
method will necessarily come prominently into use. The ob¬ 
ject of biological experimentation is the interpretation of nature, 
and, like all intelligent experimental work, it must be suggested 
and guided by observation and hypothesis. With us it is the 
oecological field in which experiment is especially called for. 
Given certain phenomena of local distribution, of relative 
abundance, of association, of habit, of variation, and the like, 
whose causes it is desirable to ascertain, it is incumbent upon 
