358 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
as are represented at / and d, wlncli have the characteristic gliding motion back and 
forth over the field among the other organisms. Great bunches of stalked forms, of 
free-living species, of bundles, and chains of many varieties of these could easily be 
added from other positions on the field under consideration, and they form also the 
prey of organisms larger than themselves. Colonies of bacteria, especially in their 
zooglea investment, are everywhere visible, and at the time when this material is 
represented the alga at h had overspread the entire inner surface of the glass. Some 
of the resting cells are shown at 5, some of the germinating ones at h. Among 
these bunches of growing alga- are the favorite resorts of many of the organisms 
heretofore described. 
If one can imagine the figures of plate 65 to be moving about upon the field of a 
microscope, each one according to its characteristic habits of living, feeding, and 
reproducing by division of each cell into two or more, among much other growing 
algm, with debris of different kinds, then some idea might be gained of the wealth of 
life which inhabits, or may inhabit, ordinary sea water in the place where this small 
quantity was taken. Just as the piles of the wharf are occupied by small animals of 
different orders — the creeping nudibranch mollusks and amphipods crawling around 
among the algte and Hydrozoa for food— and as these comprise many forms which 
branch out to ensnare their prey, as hydroids and sea- anemones, and are associated 
with many other sessile forms which create currents of water by strong appendages 
thus to bring themselves food— such as the barnacles and Bryozoa — all intertwined 
with a small forest of delicate algae of several tints and many forms; so also if we 
increase our powers of vision in the same places the same story is seen to be repeated 
by a much more numerous and diversified series of forms, of similar adaptations but 
so small as to be quite unsuspected in our ordinary means of observation by the 
unaided eye. They also consume each other in the same manner, and themselves in 
turn become the victims of other and larger foes. 
I have therefore figured these organisms heretofore described, and mentioned 
something of their habits in their environment, not with the view of adding new 
scientific descriptions or drawings to those already given by others, but rather to 
graphically call attention to the aggregate meaning of this kind of living organisms 
in their particular associations, such as make them and their cogeuers the broad staple 
food basis upon which marine life hangs. The presentation of a few of these forms 
gathered from a few drops of water especially selected, may naturally lead *o the 
consideration of the wide range of similar forms of life which one may ordinarily 
gather from the surface of the littoral waters of these localities, and may thus help to 
bring about an understanding of some of the ways in which they are interrelated, what 
precede and what depend upon them, and some of the conditions regulating the 
problems of their distribution. To do this at all broadly is at present impossible, but 
observations upon the quantity of material may be one of the steps in the process of 
understanding some of the other features attending the study, and it is the purpose 
of the following account to describe such a series of quantitative observations. 
Some of the vegetal micro-organisms, on account of the definite investment of the 
cell, as the siliceous skeleton of the diatoms, or the thick sculptured wall of the Peri- 
dinia, are the most readily preserved and distinguished in material filtered out from 
the water; moreover, they are eminently characteristic of given localities and exceed- 
ingly abundant. The following illustrations of the distribution of marine organisms 
are drawn therefore from them, to include also of minute Crustacea only the copepods 
