SOURCES OF MARINE FOOD. 
359 
as boing of wide and abundant distribution and ready recognition. Such selections of 
organisms of course will leave out many important details of distribution, for if all the 
animal organisms, larvae, other infusoria and the like, could be determined at the 
same time with these plant cells and flagellates, the two kingdoms would perhaps 
show many interrelations. But a study of these few vegetal organisms and Infusoria 
alone, in Buzzards Bay, will give some of the manifold characteristics of the Plankton 
of such a body of water. The bay itself is shallow, with broken shore line (see plate 
61), fed by many streams, of very uniform bottom, and not subject to marked tidal 
changes. 
There are also represented upon plates 66 and 67, under a magnification of 500 
diameters, some of the chief representative organisms to which the following accounts 
of distribution and quantity apply. In the tabulated estimates several genera are 
grouped together under one heading in order to simplify the plattings of quantities. 
Thus the group Melosira includes all those lettered e in plate 66, the small Cyclotella 
being classed with the other and larger forms; in estimating this group the actual 
numbers of individuals is taken, although they are often laid in short chains. So also 
the estimated Peridinia are based upon the forms p (plate 66), o, p, and /(plate 67). 
Chcetoceros takes in not only the larger forms represented at e, d, x , y of plate 67, but 
also the forms at <j (i. e., Melosira costata) on plate 66, since it is impossible, with the 
low power used in making these estimates, to distinguish perfectly the finer structure 
of these small chains, and the chain of Melosira costata , usually about the length 
represented in the upper g, is so similar in appearance under a low magnification to that 
of short chains of the small Chcetoceros that they were classed together in platting. 
This of course is an unfortunate complication in grouping and counting, and it is to be 
remembered that the Chcetoceros hereafter discussed includes at times almost wholly 
the ones here designated at g , plate 66, i. e., principally the small Melosira costata. The 
Navicula group is inclusive of all the diatoms of that general outline — Pleurosigma , 
Stauroneis, and the like, at d of plate 66, m and n of plate 67. Rhizosolenia includes 
only r of plate 67 (one individual being divided into two equal parts in this drawing). 
Many Exuvicellce are normally present, as c of plate 66. The infusoria PHnophysis (h) 
and Codonella (7c) are also readily preserved and were estimated, but the results are 
not tabulated. Many other organisms of course were common, some of which are here 
represented, while a partial classification of each one will be found in the explanation 
of plates at the close of this paper. 
Suppose now that the ship start from Station A (plate 64), at the upper extremity 
of the bay, at 11.35 a. in., September 27, being low-water slack, upon a course running 
the length of the bay and out some distance to sea (along the course A B 0 D, plate 
64). As the vessel proceeds over her course she encounters the incoming tide, there- 
fore meeting in succession any changes which may be caused by a Plankton drifting 
in from outside waters. Three samples — surface, mid-depth, and bottom — in a vertical, 
are taken at each station, from which the organisms are filtered and their results 
tabulated. At the surface of Station A (see plate 68) are found countless numbers of 
the diatoms, which will be classed with Chcetoceros (being in reality Chcetoceros plus 
the small Melosira costata ), the relative numbers of which were so numerous that 
they could not be limited by the scale here used in platting the distribution. At mid- 
depth and bottom (4 fathoms) of Station A are also found great quantities of these 
same diatoms, insomuch that other organisms are relatively few indeed. In the first 
8 miles of the course, however, from Station A to B, there is a marked diminution in 
