Page:Popular Science Monthly Volume 23.djvu/762

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742
THE POPULAR SCIENCE MONTHLY.

naked eye by shaking some of the dark-brown contents of an infested bile-duct in a glass of water and holding the vessel up to the light. The line marking off the lid of the egg may be seen near the right end,

PSM V23 D762 Egg of the liver fluke.jpg
Fig. 2.

and a little to the left is the embryo in its early state of development. It is surrounded by large granular masses, which serve as food. Only three of these masses, at the left hand, have been fully drawn. In one case Professor Thomas found seven million eggs in the gall-bladder of

PSM V23 D762 Fully developed fluke egg and the cilia for water propulsion.jpg
Fig. 3. Fig. 4.

a single sheep, while the liver contained about two hundred flukes. The number of eggs produced by a single fluke may be safely estimated as half a million. No further changes take place in the egg