Saikingaku Zasshi = Journal of Bacteriology
Eggs of Paragonimus westermanii hatch in water in from 25 to 28 days. The miracidia attack Melania libertina and M. obliquegranosa. Later these exhibit cercariae similar to those found in snails under natural conditions. The stylet of these cercariae is similar to that of the encysted cercariae found in the crab Potamon (Geothelphusa) obtusipes. In the liver of the snails the miracidia become sporocysts and these give rise to cercariae. No redia has been noted. In the early stages in the crab the young forms measure 0.13 mm. in length by 0.05 mm. in breadth. The oral sucker measures 0.04 mm. in diameter and is armed with a stylet. The ventral sucker is 0.02 mm. A thin sac now encloses the worm which is completely bent upon itself. This sac has a diameter of 0.11 mm. and the pharynx and excretory organs become evident. The mature cyst measures 0.3 mm. to 0.4 mm. in diameter and its walls have a thickness of 0.09 mm. to 0.014 mm. By this time the worm is straight, short and fat; not bent upon itself. The oral sucker has a diameter of 0.07-0.09 mm. and the ventral sucker 0.09-0.11 mm. These encysted cercariae are said to pass to man on the eating of infected crab or possibly in some free form.
R. T. L.
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