276 THE OVARIAN EGG. 



indeed, in all eggs, but in those which produce 

 but one individual is only a stage in the natural 

 growth of the yolk during its transformation into 

 a young embryo. As the facts here alluded to 

 are not very familiar, even to professional natural- 

 ists, I may be permitted to describe them more 

 in detail. 



No one who has often walked across a sand- 

 beach in summer can have failed to remark what 

 the children call " sand saucers." The name is 

 not a bad one, with the exception that the saucer 

 lacks a bottom ; but the form of these circular 

 bands of sand is certainly very like a saucer with 

 the bottom knocked out. Hold one of them 

 against the light and you will see that it is com- 

 posed of countless transparent spheres, each of 

 the size of a small pin's head. These are the 

 eggs of our common Natica or Sea-Snail. Any 

 one who remembers the outline of this shell will 

 easily understand the process by which its eggs 

 are left lying on the beach in the form I have 

 described. They are laid in the shape of a broad, 

 short ribbon, pressed between the mantle of the 

 animal and its shell, and, passing out, they cover 

 the exterior of the shell, over which they are 

 rolled up, with a kind of glutinous envelope, 

 for the eggs are held together by a soft gluti- 

 nous substance. Thus surrounded, the Natica, 

 whose habit is to burrow under the surface of 



