1885.] NEW-YORK MICROSCOPICAL SOCIETY, 67 



I thought we would examine that bottom, and, to my surprise, 

 we took up these two oysters, which evidently were left of that 

 planting thirty years ago. I opened them, and they proved to 

 be of fair quality." Does not this agreement between the 

 naturalist and the oysterman deserve to be called a demonstra- 

 tion ? 



How does the oyster begin life ? I shall now speak only of the 

 American oyster, whose earliest babyhood is so different from 

 that of the English mollusk — since theirs is emitted in an ad- 

 vanced stage of development, while ours is emitted simply as an 

 egg. In the r-less months, our oyster-beds are, many of them, 

 marked by the appearance of little clouds of a milky hue. These 

 proceed from the female oyster, which snaps its shell, and thus 

 emits its spawn into the water. The male, in like way, emits the 

 fecundating milt ; but, to the eye, this is invisible. The eggs, 

 sinking to the bottom, fall in with some of the milt in the water, 

 and the spermatoza at once attach themselves to them. As seen 

 under the microscope, the tiny egg becomes like a bur ; that is, 

 as if it were beset on the surface with cilia. In a word, it is 

 fecundated, and with this addition of life it mounts up from its 

 bed and floats away. In two or three hours the egg is hatched, 

 and the development of the little creature begins. At first, it is 

 a little triangular thing. It now begins to swim actively. But 

 how does it do it ? From what we might call the base of the angle 

 which outlines the little thing, you see a pad projecting. Really 

 it is a brush of cilia, every individual of which is lashing its way 

 with the force of a projectile. In a very few hours a spot ap- 

 pears on each side of the apex of the triangle. Each spot is the 

 beginning of a shell, or valve ; and the fact of its beginning 

 where it does, at what we have already called the umbo, has 

 caused Dr. John Ryder to name this the umbo stage of the 

 oyster's life. Nature in her work with an egg seems to delight 

 in developing toward a side. In this way she starts a fish, a rep- 

 tile, a bird, and a mammal. But our "midget" oyster is per- 

 fectly symmetrical — each valve, or side, is the exact counterpart 

 of the other. 



This roving life of the embryo oyster exposes it to infinite 

 perils. It is certain that of the twenty or thirty millions of eggs 

 emitted, not more than an average of two or three individuals 

 will attain a size fit for the market. If all were to survive, such 



