THE OYSTER. 47 



The number of male cells which a single male will 

 yield is great beyond all power of expression, but the 

 number of eggs which an average female will furnish 

 may be estimated with sufficient exactness. An un- 

 usually large American oyster will yield nearly a 

 cubic inch of eggs, and if these were all in absolute 

 contact with each other, and there were no portions of 

 the ovaries or other organs mixed with them, the 

 cubic inch would contain 500^, or 125,000,000. Di- 

 viding this by two, to allow for foreign matter, inter- 

 spaces and errors of measurement, we have about 

 60,000,000 as the possible number of eggs from a 

 single very large oyster. 



I have shown that, by mixing eggs extracted from 

 a female with male cells, it is an easy matter to secure 

 their union in a watch crystal or in a glass beaker. 



The body of the oyster, like that of all animals, 

 except the very simplest, is made up of organs, such 

 as the heart, digestive organs, gills and reproductive 

 organs, and these organs are at some period in the 

 life of the oyster made up of microscopic cells. Each 

 of these consists of a layer of protoplasm around a 

 central nucleus, which, in the ^^^y is a large, cir- 

 cular, transparent body, known as the germinative 

 vesicle. Each cell of the body is able to absorb food, 

 to grow, and to multiply by division, and thus to con- 

 tribute to the growth of the organ of which it forms a 

 part. The ovarian eggs are simply the cells of an 

 organ of the body, the ovary, and, so far as the micro- 

 scope shows, they differ from the ordinary cells only 

 in being much larger and more distinct from each 

 other; and they have the power, when detached from 



