(il) The Ireslicr the eggs the greater their efFeet in shortening this period, hnt the 

 t\vo parts of postmarine age, viz, the days before opening and the days after open- 

 ing, have nne(|nal iufluenee. Days after opening have less eft'ect to shorten tho 

 period tliau days before opening. 



(12) Fresliening of oysters rcfluces the vitality of spermatozoa. 



(43) The ability of siierniatozoa to fertilize eggs deereases with postmarine age, 

 and after 2 or 3 days the results are no longer satisfactory, althongh develojunent 

 is caused for some time later, jet this development shows a gradually descend- 

 ing scale of power as age increases. 



(•li) In 2 or 3 days tho active period of spermatozoa is reduced one half; it follows 

 that sitermatozoa can suffer a weakening of 50 per cent of their vitality before losing 

 the power to cause at least fair results in fertilization and development. 



3Vi<! eggs. — (45) Eggs are, at every point where environment influences them, more 

 sensitive than spermatozoa, 



(46) Eggs do not survive the death of tho oyster unless the oyster be opened 

 fresh. 



(47) In oysters over 2 days old the eggs fail to produce cniliryos but rapidly decom- 

 pose in the sea water (oyster still alive). 



(48) Fresh eggs, unfertilized, remain in sea water for several days before yielding 

 to decomposing forces. 



(49) In solutions weaker than normal and in proportion to the dilution, fresh eggg 

 decompose rajiidly, passing through stages of swelling. 



(.50) In solutions stronger than normal, fresh eggs shrink, and finally also decom- 

 pose with rapidity. 



(60) Freshening of oysters acts very strongly to produce deterioration of eggs. 

 Sometimes the eggs are as far gone when the oyster is first received as if the oyster 

 (unfresln'ned) had been kept over 2 days. 



(61) Eggs in oysters of only 1 day's postmarine age show (a) a great decrease in 

 the number of eggs fertilizable, and (h) a partial and abortive development. 



"(62) Fresh eggs can remain in normal sea water over an hour liefore fertilization 

 without losing the power of being fertilized and of developing. 



(63) Some partial and abnormal development takes place even after 2;J^ hours' 

 soaking before fertilization. 



(M) .Solutions weaker or stronger than normal (a) decrease the jteriod eggs can 

 remain unfertilized without deterioration, or (b) if the period be the same, the 

 results in development are correspondingly unsatisfactory, poor, or nil. 



(65) Temperatures favorable to development range from 70° to 100^', with a jirobable 

 optimum near 85° F. 



{G6) Increase in temperature rapidly increases the rate of development by about 

 double for every 10°. 



Emhrijos. — (67) Embryos can not be readilj' kept to the time of fixation without 

 th«^ assistance of a claire to furnish food. 



(68) Embryos seem to be attacked by the infusorial parasites from the stomach, 

 • tc, of the adult oyster. 



(69) At average temperatures vigorous embryos are all at the surfiice from 

 one half to three quarters, or 1 day, and can be readily separated from doliris and 

 si'diment at such time. 



(70) Many embryos fail to become free-swimming. 



(71) No satisfactory way of separating good eggs from bad ones in oyster culture 

 was discovered. 



(72) Eggs sink in sea water at a rate of nearly 1 foot per hour. (This can betaken 

 advantage of in cleaning eggs by stratification.) 



(73) Spawn is dispersed mainly by tidal currents during the short period tho 

 embryo swims at the surface. 



