156 MARVELS OF FISH LIFE 
and barnacle larve still remain (in a somewhat altered 
form), the larve of star-fishes, urchins, and numerous 
others are now added to the sea. 
Thus it will be seen that in the spring and autumn 
the sea is a mass of minute animal and vegetable life. 
In the spring the larval fish mainly feed upon the 
diatoms, and later on in the year to a great extent upon 
the larve of various marine animals. 
The smaller forms of plankton life can only be 
collected in a net with a very fine mesh, but if any of my 
readers are anxious to examine plankton under the 
microscope, it is not difficult to make a net of No. 20 
bolting cloth, which can be purchased from flour milling 
engineers. When at the seaside such a net slowly 
towed behind a boat, will bring up many quaint forms 
of life, but at times the main catch may be almost 
entirely a large round protozoan, about a twenty-fifth 
of an inch in diameter, known as noctiluca; this, when 
seen for the first time, may be mistaken for a fish’s 
egg. The phosphorescence in the sea on a summer’s 
night is due to these protozoa. If a spoonful or two 
of the noctiluca be collected as described and spread 
out on a piece of blotting paper, it is quite easy to 
read by the light given off from them. Noctiluca, like 
diatoms, at certain seasons increase with miraculous 
rapidity, and by daylight may cause the sea to appear 
of a reddish-brown colour. 
As the water in the sea swarms with plankton, so 
the bottom of the sea is carpeted with teeming lile ; 
