Page:Popular Science Monthly Volume 71.djvu/370

364, has elongated, acquired-a peculiar form, and here in the interior are lighter and darker spots. These do not show very clearly in the picture, because it is from a photograph of a living specimen under the microscope. The lighter and darker spots correspond to the details in the structure of the organism. Here is the tail of the organism, twisted, as you see, and in life capable of being bent. The movement of the animals in the natural fluid in which they are suspended is quite active. Alongside are some blood corpuscles, the figure, as you see, is magnified about the same as the one of the malarial parasite which I showed you a few moments ago. The next slide exhibits an

organism which swims free in the water, and is pretty well shown in this figure. It is called the Stentor. Here the chain of beads represents the nucleus. Upon the surface of the body there are fine lines indicating superficial structure. At this point there occurs what we call the mouth. Over the rest of this minute organism there is a thin cuticle, but at the mouth the cuticle is absent, and the protoplasm is naked or uncovered so that food can be taken in. There are bands of hairs showing coarse and stiff in the figure but capable of movement, and with the aid of those vibratile hairs, or cilia, the organism can swim about in water. Here is another internal structure, the vacuole; obviously in an animal like this we no longer have simple protoplasm