Page:Popular Science Monthly Volume 6.djvu/361

Rh space or vacuole, no "eye-spot," no eyelashes or cilia, and when it is quite fresh and new you cannot see any kernel or nucleus. You really can see nothing but an odd-looking lump, with here and there some little grains inside of it. If you give it a drop of weak vinegar or acetic acid, the little grains will disappear, and you can see the kernel in the centre (Figs. 18, 19).

You can find this kernel much easier if you stain the cell with magenta or weak iodine. Heat makes these amœbæ or blood-cells move

much quicker, and it is very interesting to watch them make their way among the yellowish-red cells which lie in rows all around them. Sometimes one of the amœbæ will clear a channel for itself right through a thick group of the others. The first time I ever saw them moving in this way, I could not help thinking of the canals in Venice, where the gondoliers steer their gondolas close beside the houses, turning the corners so skillfully as never to strike them. So these little gondoliers of the blood went in and out, threading their way among the reddish-yellow cells, which stood in rows on either side the narrow channels (Fig. 20). There is one great difference, though: in Venice



the gondolier has nothing to do but follow the canals that are made for him, but the amœbæ gondolier has to make his way as he goes. No wonder you open your eyes! It is enough to open any one's eyes to think of the thousands of these odd creatures that go half creeping, half walking through one's veins. You know people sometimes talk about their "blood crawling," but very few people know how the blood crawls.

If you heat the amœbæ they pull in all their little feet and become perfectly white and still, and nothing you can do will ever bring