1 42 RHYTHM 



a similar lunar rhythm and the popular belief that they do 

 may possibly be due to the fact that in very early times the 

 Egyptians, exceptionally able people, noted the fact that the 

 Red Sea urchins had a lunar period, and generalizing too 

 widely spread the view amongst the Greeks and Romans. 



The influence of the moon on the food supply of the people 

 is shown by the "Grunion," a small smelt some 6 inches long 

 w^hich occurs on the sandy shores of California on the second, 

 third, and fourth nights after the full moon, during the big 

 tides from March till June. These little fish come ashore on 

 the top of a wave, lie for a moment on the sand, and drop 

 back into the sea with the succeeding wave. Hundreds of 

 people assemble to pick up and catch these fish in the moon- 

 light, using screens, seines, and their hands. The object of the 

 people is of course to get food, but the object of the fish is to 

 spawn. The eggs are laid in small masses 3J inches below the 

 surface just above the limit of the average tide. They even 

 form the food of a small terrestrial beetle. Ten days after 

 spawning and one day before the next high tide the eggs are 

 washed out of the sand, hatched, and the larvae escape into 

 the surf. The whole procedure is wonderfully timed and 

 adjusted so that the fish have just enough time on land to 

 lay and bury their eggs. The "run" of the fish begins about 

 the turn of the tide. Otherwise, eggs laid an hour too early 

 would be washed away. 



Rhythm in Organisms 



Bacteria and Protozoa exist in the soil, as we have seen, 

 in incredible numbers. They do not remain the same in 

 number from day to day and the fluctuations are great, but, 

 so far, have not been associated with any definite external 

 factors. They do, however, show a certain fortnightly rhythm, 

 and both bacteria and protozoa which prey upon bacteria 

 are most numerous at the end of November and at a minimum 

 during February. But so far these changes have not been 

 associated with temperature or rainfall. 



Amongst the numerous organisms which were investigated 

 at the Rothamsted Agricultural Experimental Station every 

 day for a whole year is a flagellate, known as Oikomonas, and 



