50 DARWINISM AND HUMAN LIFE 



food for minute Infusorians, wHicli multiply so 

 rapidly that there may be a million from one in 

 a week's time. 4 cataract of Infusorians over- 

 flowed from box to pond, an(L.tlie water-fleas and 

 other small fry gathered at the foot of the fall 

 and multiphed 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 Crus- 

 tacean, which became part of the fish, which 

 became part of the man. And it is thus that 

 the world goes round. 



Correlation between Catches op 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. BuUen ^ 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 neighbourhood of the mackerel 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 Infusorian-like organisms 

 called Peridinidae. But the production of this 

 microscopic plankton, the " stock ." of the "sea- 

 soup," depends partly on the composition of the 



^ Journ. Marine Biol. Assoc. (1909), voL viii. p. 394 



a Ibid. p. 269. 



* Internal. Revue Hydrobiologie (1908), voL L 



