306 American Fisheries Society 



selves. The problem of getting the seed has become very difficult in 

 recent years. The amount of seed, rather than the amount of ground, 

 naturally determines the amount of the product, and any system which 

 will develop or increase the amount of seed will, of course, increase the 

 total product in direct proportion. 



Earlier investigators had isolated information as to the different 

 events in the oyster's life, while we obtained a continuous series of 

 accurate observations in their proper sequence and were, therefore, able 

 to determine the time intervals corresponding to the different stages of 

 development. Unfortunately, with all that wealth of material we were 

 not able to do more than hurry along and take what we could, the period 

 of the oyster's growth, of course, determining the time that we could 

 devote to our investigation. 



After the oyster egg is fertilized a period of about six hours elapses 

 before it can swim around in the water — six to nine, depending on the 

 temperature. At that stage it looks like a microscopic blackberry, being 

 divided into small cells. A little later it begins to grow a shell, the 

 time depending on the temperatuFe ; in some cases the shell appears 

 more rapidly than in others, but after a couple of days (sometimes in 

 twenty-four hours) it will be covered with thin transparent shell. 

 Oysters were reared to this stage by Prof. W. K. Brooks. I would call 

 it the termination of the embryonic stage of the oyster, which up to 

 this time has lived entirely upon the material in the egg, and has shown 

 no sign of increasing in size. Several investigators have carried the 

 oyster through the embryonic stage, but so far as I can find, no one 

 has ever shown any evidence of bringing it to the next critical stage in 

 which it obtains food from the water and grows. I would compare it 

 to the difference between the chick when it breaks from the shell and 

 the brooder chick which you have every reason to believe will, if left 

 alone, become full-grown. 



The next stage is marked by a new growth of shell, having a cres- 

 cent moon effect, around the edge of the embryonic shell. What I call 

 the crescent moon stage, then, marks the scientific distinction between 

 the embryo and the larva, the embryonic stage being divided into the 

 pre-shell and the shell stage. The embryonic shell has a straight hinge 

 and is known as the straight-hinged stage. The larval stage extends 

 from the embryonic to the time the oyster attaches or "sets," which has 

 been called the dissoconch stage. The early larva looks like a trans- 

 parent soft clam, but as it develops becomes more round and deeper 

 until it exactly resembles a hard clam. 



