OYSTERS AND METHODS OF OYSTER-CULTURE. 269 



together with the various waste products resulting from digestion and 

 respiration. 



The season at which oysters spawn differs with the latitude of the 

 bed and with local conditions. As a general rule, it may be said that 

 they ripen earlier in the south than in the north, and that in the same 

 region the genital products mature earlier in shallow than in deep water. 

 These facts appear to be dependent primarily upon the temperature, 

 other things being equal, southern waters warming before the northern, 

 and the shallows before the depths. 



It is stated that the raccoon oyster of South Carolina spawns from 

 the middle of March to the middle of August. Eipe individuals are 

 found in shallow- water creeks during January and February, and it 

 is probable that intermittent spawning may take place at any time 

 during the year when favorable conditions prevail. In Chesapeake Bay 

 oysters are found spawning from April to October, but apparently a 

 few scattered individuals spawn at other times, though most of the spawn 

 appears to be cast during the latter part of July or early in August. 

 In Long Island Sound spawning takes place, according to the locality, 

 during May, June, July, and August. Sometimes many oysters are 

 found with well-developed ova during April, but this appears to be 

 unusual, and Dr. Dean remarks that when it occurs "it will almost 

 invariably be found that the spring has been warm and dry." 



Not only the time of spawning, but the quantity of spawn, appears 

 to be affected by the weather conditions. Sudden changes produce 

 very marked results, and a transfer of the oyster from one place to 

 another during the spawning season is almost certain to interfere with 

 reproduction or even absolutely arrest it. 



The age at which the oyster becomes capable of reproducing its kind 

 varies with the locality, but it appears that in regions of rapid growth 

 the generative organs ripen during the first year. The number of eggs 

 discharged by the female is naturally dependent upon its size. Accord- 

 ing to Dr. Brooks, the Maryland oyster of average size produces 

 1(),000,000 eggs each year, while a very large individual may produce 

 G0,000,000. The spermatozoa, being extremely minute, are present in 

 the milt in inconceivable numbers. 



jSTotwithstanding the great fecundity of the individual oyster the 

 reproductive power of the beds is not so vast as is generally supposed. 

 If the oysters are scattered, or the number spawning at a given time is 

 small, most of the genital matter will be wasted, as the contact of the 

 male and female cells is entirely dependent upon chance, and the fewev 

 such cells there are in a given body of water the smaller the probability 

 of their meeting and fusing in the manner constituting the act of fer- 

 tilization. Neither the eggs nor the spermatozoa live long after they 

 are discharged from the parent, and if fertilization is to take place at 

 all the two elements must be brought into contact promptly ; and it will 

 be seen, therefore, that nature must supply a vast number of germ cells 

 to insure the survival of but a few. 



