SUN AND HARVEST OF THE SEA—SCH MITT 301 
which they have been concerned, chiefly in the North Temperate Zone, 
where some of the world’s greatest fisheries are found. On the basis 
of a very rich diatom haul in Kiel Bay, the marine biologist Brandt 
calculated that the estimated 114 cubic meters of water that passed 
through the silk net on that occasion contained about 9,000 millions 
of diatoms, or about 6,000 per cubic centimeter. Hensen, working 
in the west Baltic Sea, estimated the average number of diatoms 
in that area to be about 457 millions per cubic meter, or 457 per cubic 
centimeter. Apstein found the commonest species of dinoflagellates 
to be less numerous than diatoms, but that, even so, they occurred 
at the rate of from 1 to 10 million for each square meter of the surface. 
In the Skager-Rak, in Norway, Gran estimated on the basis of another 
rich diatom haul that there was at the time an average of 228 million 
diatoms per square meter of surface in that body of water. An 
American, Peck, as the result of a quantitative study made at Woods 
Hole and in Buzzards Bay, claimed a total of some 420 million diatoms 
per cubic meter of sea water for some of his largest catches. Herdman 
and his associates, working in the Irish Sea, have made many interest- 
ing contributions to our knowledge of marine biology. They tell of 
several notable diatom catches made with small nets in brief tows, 
netting on one occasion 150 millions of Chaetoceras and on another 
180 millions of Rhizosolenia. Moore, from a study of the carbon di- 
oxide consumption of the phytoplankton of a 16-square-mile area 
of the Irish Sea, estimated that this area produced on the average 
2 tons of dry organic matter, equal to 10 tons of moist vegetation 
per acre, a yield that does not compare unfavorably with the yield 
of cultivated land. Bigelow, in his report on the plankton of the 
Gulf of Maine, figuratively throws up his hands at the futility of 
calculating the abundance of phytoplankton, saying that, “When 
such numbers‘ as I have listed as examples are expanded from the 
trifling bulk of a cubic meter of water to cover the 36,000-square- 
mile area of the Gulf of Maine north of its offshore banks and to a 
stratum at least 20 meters thick, they become too vast for the human 
mind to envisage.” 
In general, the chemical composition of the crops of the sea is not 
so very unlike average meadow hay. Diatoms, the most studied con- 
stituents of the phytoplankton, show about the same proteid and fat 
content, somewhat lower carbohydrate content, but considerably more 
ash due to their siliceous shells; the peridinians very closely approxi- 
mate better than average meadow hay in proteid and carbohydrate 
content, though falling a little below in fat and ash.5 
*These numbers are based on the number of cubic centimeters of plankton taken per 
standard half-hour haul of a No. 18, 0.079-millimeter-mesh silk net. These catches varied 
from very meager ones to some containing nearly 600 cubic centimeters of plankton. 
© After Johnstone. 
