LIFE'S SIMPLEST CHILDREN. 19 
And now, before we go on to other forms, let me 
ask you to pause and think what these little slime- 
specks tell us about the wonderful powers of Life. 
Can you guess at all how these creatures do their 
work ? We are obliged to have eyes to see our food, 
nerves and muscles to enable us to feel and grasp it, 
mouths to eat it, stomachs which secrete a juice in 
order to dissolve it, and a special pump, the heart, to 
drive it into the different parts of our body. But in 
these tiny slime-animals life has nothing better to 
work with than a mere drop of living matter, which 
is all alike throughout, so that if you broke it into 
twenty pieces every piece would be as much a living 
being as the whole drop. And yet by means of the 
wonderful gift of life, this slime-drop lives, and 
breathes, and eats, and increases, shrinks away if you 
touch it, feels for its food, and moves from place to 
place, changing its shape to form limbs and feeling- 
threads, which are lost again as soon as it no longer 
needs them. 
Nor have we yet learnt one-half of the marvels 
which can be wrought in living specks of slime. For, 
on further inquiry, we find these simple forms de- 
veloping two quite different modes of life. In the 
one case the slime is moulded itself into delicate 
forms, making creatures with mouths, with suckers, 
and with delicate lashes to drive the body through 
the water ; while in the other case, remaining a simple 
drop with delicate threads, it has learned to build a 
solid covering of the most exquisite delicacy. 
To the first class belongs our little Noctiluca, and 
the forms drawn by its side in Fig. 3. To the second 
belong the microscopic shells (Fig. 4) which form our 
