82 SECRETS OF ANIMAL LIFE 
meadows.” On the Beagle voyage Darwin was 
impressed off the coast of South America with vast 
tracts of water discolored by the minute floating 
Algz, the “ sea-sawdust ” of Captain Cook’s sailors, 
and since the days of the Challenger information in 
regard to the Phyto-plankton has grown apace. It 
seems to be the food of many open-sea animals, 
such as small Crustaceans, which again are devoured 
by young fishes. The growth of the sea-meadows 
in spring is thus as important as the garment of 
green on the farmer’s fields. Professor Herdman 
of Liverpool, a leading authority on the biology of 
the sea, cites the calculation that a Diatom “less 
than the head of a pin, dividing into two at the 
normal rate of five times in the day, would at the 
end of a month form a mass of living matter a 
million times as big as the sun. The destruction 
that keeps such a rate of reproduction in check 
must be equally astonishing.” It should be 
noticed, however, that considerable evidence is 
accumulating in support of the view that the 
minute constituents of the Phyto-plankton are even 
more important in their death than in their life. 
For when they are killed by changes of temperature 
and the like, or when they reach the end of their 
natural tether, they add to the valuable organic 
detritus which remains in suspension in the water 
or sinks to the floor of the sea. To this accumula- 
tion of organic débris very important contributions 
are also made from the littoral belt of seaweed and 
sea-grass. Indeed, recent investigations by two 
