54 THE WORLD OF THE SEA. 
imperceptible to the human eye. These microscopic creatures are, 
in short, the smallest and the most numerous creatures in nature. 
They constitute, with human beings, one of the wheels of that very 
complicated machine, the globe. They fill that rank and station 
willed for them by the great first Thought! Suppress these 
beings and the world would be incomplete. And so the old saying 
comes true, “ There is nothing so small but may become great 
by reflection.” 
These infusoria are more or less transparent. They have not 
INFUSORIA, COTHURNIA. 
Cothurnia pyxidif~ormis. ) 
enough substance to be opaque. Their bodies are generally glo- 
bular or ovoid ; sometimes they are oblong, sometimes blister-like, 
sometimes a flattened disc, and even thin as a leaf. They are found 
resembling a tadpole, a thimble, a little bell, a shoe, a rose-bud, a 
flower, a grain of wheat. 
The Monads, the least of the least, appear only to be molecules 
of an absorbing substance, live atoms, points which exist. These 
tiny creatures are in diameter about the gsooduoooth of an inch! 
At first it was supposed that the infusoria were utterly destitute 
of any kind of organisation. They were thought to be fed by 
absorption, and by absorption only, but it has lately been discovered 
that certain species are complicated enough. There are some—the 
Polygastrica—which have not less than four distinct stomachs, thus 
