THE OPEN SEA 69 
the circulation of matter, we must always be- 
gin with the plants. 
In most parts of the sea, wherever the sun- 
light penetrates and the temperature is not too 
low, there are countless myriads of simple 
plants, ‘“‘scattered like dust amid the immeas- 
urable water masses.” ‘These minute marine 
_ Alge are not visible to the naked eye, and it 
is only within comparatively recent times that 
their abundance, and their great importance 
in the chain of life in the ocean, have been 
fully recognised. Between Australia and New 
Zealand, we are told, the officers of the Chal- 
lenger, the ship of the great ocean expedition 
sent out by the British Government in 1873- 
1876, found the water “continuously discol- 
oured during a period of several days’ sailing, 
and giving off the odour of a reedy pond.” 
Elsewhere too, even in the Arctic Regions, 
the water is sometimes ‘‘as thick as soup.” 
Along with the minute Alge there are many 
minute animals (Infusorians) which have got 
possession of the green pigment chlorophyll, 
and there are others (Radiolarians) which 
have Alge living in partnership with them. 
All these form part of the fundamental food- 
supply of the open sea. They are eaten by 
