BACKGROUND OF DARWINISM—THE WEB OF LIFE 200 
worked in the mud and manure, making food for minute Infusorians 
which multiply so rapidly that there may be a million from one in a 
week’s time. A cataract of Infusorians overflowed from box to pond, 
and the water-fleas and other small fry gathered at the foot of the fall 
and multiplied exceedingly. Thus the fishes were fed, and, as fish- 
flesh is said to be good for the brain, we can trace a nexus from mud to 
clear thinking. What was in the mud became part of the Infusorian, 
which became part of the Crustacean, which became part of the fish, 
which became part of the man. And it is thus that the world goes 
round. 
Correlation between catches of mackerel and amount of spring 
sunlight—A curious and most interesting correlation has been 
discovered by Dr. E. J. Allen between catches of mackerel and the 
amount of sunlight. The more sunshine in May, the more mackerel 
at Billingsgate. How does this work out? Mr. G. E. Bullen shows 
that “for the years 1903-1907 there appears to be a correlation 
between the number of mackerel taken during May, and the amount 
of Copepod plankton, upon which the mackerel feed, taken in the 
neighborhood of the fishing grounds during the same month.” 
Mr. W. J. Dakin shows that the food of Copepods consists largely 
of the vegetable organisms of the plankton, such as diatoms, and of 
Infusoria-like organisms called Peridinidae. But the production of 
this microscopic plankton, the ‘“‘stock”’ of the “seasoup,” depends 
partly on the composition of the sea-water, partly on the tempera- 
ture, and partly on the amount of light available. There seems to be 
no correlation between the surface temperature and the abundance 
of mackerel, but Dr. Allen has shown a correspondence between 
sunshine and the catches. Thus we see that, if all flesh is grass, 
then in the same sense all fish is diatom. 
Nutritive chains in the deep sea.—If we pass from the sunlit 
open sea to the floor of the deep sea—that strange, dark, cold, silent, 
plantless world—we find carnivorous animal preying upon carnivorous 
animal through long series—fish feeds on fish, fish on Crustacean, 
Crustacean on worm, worm on stil] smaller fry, and all ultimately 
depend on the basal food-supply—the ceaseless shower of moribund 
atomies sinking from the surface waters many miles, it may be, over- 
head, like the snowflakes on a quiet winter day. 
Dependence of one organism on another for the continuance of 
the species.—Passing from ‘nutritive chains,’ we may select a few 
illustrations of the dependence of one creature upon another for the 
