46 THE OYSTER, 



that the ripe eggs ooze from the openings of the 

 oviducts before the mass is quite at the point of 

 being discharged. If the point of a knife be pushed 

 into the swollen ovary, a milk white fluid will flow 

 out of the cut. Mixing a little of this with sea water, 

 and placing it on a slide underneath a cover, a lens of 

 100 diameters will show, if the specimen is a female, 

 that the white fluid is almost entirely made up of 

 irregular, pear-shaped, ovarian eggs, each of which 

 contains a large, circular, transparent, germinative 

 vesicle, surrounded by a layer of a granular, slightly 

 opaque yolk. Perfectly ripe eggs will be seen to be 

 clean, sharply defined, and separate from each other. 

 If the specimen be male, a glance through the micro- 

 scope shows something quite different from the fluid 

 of a female. There are no large bodies like the eggs, 

 but the fluid is filled with innumerable numbers of 

 minute granules, which are so small that they are 

 barely visible when magnified lOO diameters. They 

 are not uniformly distributed, but are much more 

 numerous at some points than at others, and for this 

 reason the fluid has a cloudy or curdled appearance. 

 By selecting a place where the granules are few and 

 pretty well scattered, very careful watching will show 

 that each of them has a lively, dancing motion, and 

 examination with a power of 500 diameters will show 

 that each of them is tadpole-shaped, and consists of a 

 small, oval, sharply defined *' head," and a long, deli- 

 cate ** tail," by the lashing of which the dancing is pro- 

 duced. These are the male cells, whose union with 

 the eggs or ova of the female is necessary to the fer- 

 tilization of the latter, and the consequent hatching of 

 living oysters. 



