Page:Popular Science Monthly Volume 6.djvu/359

Rh boats often have a tiny red window, or port-hole, called the "eye-spot." If you watch long and carefully, you can see the little boat-man pull in his oars (Fig. 12), as if to rest. But, if you shake the water, and then put it in the sun, out go the oars again, rowing faster than ever. The little pear-shaped cells do not have a tough, cellular sac; these independent little sailors seem to jump out of the boats

entirely and swim about quite naked (Fig. 13). After they have bathed to their hearts' content, they seem to retire quietly to the sands and dress themselves again; that is, each one builds around himself a new wall, or boat, in which he rests till he needs another dip. The larger kind try to be more respectable; they stay in their boats in a dignified and proper manner. Iodine kills them, and then you can see where the little oars are pushed through the row-locks in the sides of the boat. These oars are called cilia—a word which



means eyelashes. When the little sailors are getting tired, and just before they die, you can see these eyelash oars quite plainly, they move so slowly; but, when they are vigorous and the day is sunny, the oars move so fast you cannot see them. No Columbia or Cambridge crew can begin to pull with these protococcus boatmen. Besides being good oarsmen, they are also good builders. You may often see them breaking up the old boats by cleavage and fission, just as the carpenters break up the old houses.

And so we have followed our quaint little friend, the protococcus, through all his occupations chemist, carpenter, boatman, and ship-builder. Now, I am sure you will never again pass by an old fence, or a pool of green water, without thinking of the wonderful little