115 
ten minutes the boat would thus have traveled 880 feet. 
The area of the opening of the net is 100 square inches, or 
.75 of a square foot. In ten minutes the net thus strained 
880 x .75 — 660 cubic feet of water. Since about 10 per 
cent. of the water passes over the edge of the net, and not 
through it, we may say, in round numbers, that the net 
strained 600 cubic feet of water in each haul of ten min- 
utes. The material thus collected was preserved in alcohol 
for future examination. 
This examination showed that in every case the take 
consisted almost wholly of two things. First, there were 
immense numbers of those minute, microscopic plants, the 
diatoms, and besides these almost nothing but entomos- 
traca. These entomostraca have not been studied suffi- 
ciently to determine the species to which they belong, but a 
glance suffices to show that they nearly all belong to the 
one family of Calanida, which of all our copepoda are 
best adapted to lead a roving life in deep water and far 
from shore. In this connection, it is worth while to note 
that the Calanide@ live almost altogether on diatoms and 
other minute alge. These alge, in their turn, get their 
nourishment from the inorganic matter in solution in the 
water, matter which the waves wash from the soil along 
the shore and which the rivers bring down through long 
distances. If the alge are thus nourished by the sub- 
stances in solution in the water, if the Ca/anid@ feed on 
alez and the young fish on Calanida@, we have a very per- 
tinent illustration of the conversion of the constituents of 
the soil into fish-flesh. 
After having thus determined roughly the character of 
the material found in each locality, that obtained at each 
haul of the net was placed in a graduated glass cylinder 
and measured. 
The following table from my note book is a complete 
record of the work done: 

