[7] EXPERIMENTS IN OYSTER CULTURE RYDER. 769 



iuto the water. I find that the masses of eggs when squeezed from the 

 oviducts and dropped into clear water immediately dissociate and dif- 

 fuse themselves as a uniformly granular cloud if the eggs are perfectly 

 ripe. If the eggs are not perfectly ripe, they do not separate so readily, 

 but tend to adhere together in masses. This accordingly becomes a most 

 excellent test to determine the degree of maturity of the ova; a very 

 important practical point in the artificial method of culture yet to be 

 developed. 



The milt or semen of the oyster is stringy and flocculent when dropped 

 into clear water. If stirred the masses break up into wisps and stringy 

 clouds before mixing intimately with the water. When the admixt- 

 ure is complete the water charged with milt assumes an opalescent or 

 bluish-white tint. In practice it is found best to use a very dilute mixt- 

 ure of water and milt for purposes of artificial fertilization, the ijhi- 

 losophy of which is this : One spermatic j)article only is needed to 

 fertilize an embryo; the spermatozoa are vastly — a thousand fold — more 

 numerous than the ova. A superabundance of spermatozoa used in 

 the process of fertilization simply causes the eggs to be covered with 

 them. The ineffectual ones on the outside of the egg eventually die and 

 putrefy and needlessly pollute the water in which the eggs undergo 

 their development. 



The lot of oyster ova impregnated at 10.30 a. m. to day are already 

 swimming, and have reached the stage at which the micromeres have 

 included the macromeres. The development attained so for has re- 

 quired five hours. 



July 18. — Temperature of water to-day ranged from 75° F. to 84° F. 

 Another lot of eggs were impregnated this morning. Embryos of the 

 17th not doing so well at 3 p. m. to-day. Was probably not careful 

 enough to get rid of superfluous milt. Filters still hold the embryos, 

 but many of them have threads of slimy matter hanging to them, with 

 blister-like protuberances, which are abnormal, due probably to imper- 

 fect renovation, aeration and purification of the water, and accumulation 

 of slimy sediment in the jars and aquaria. I fertilized another large 

 lot at 12 m. to-day, using nineteen adults in the operation. 



July 19. — Oyster embryos of 17th and 18th diminishing in numbers 

 rapidly. Amcebse and Infusoria are beginning to make their appear- 

 ance in the aquaria. The mortality of the embryos is surprising, and 

 as yet I see no sure way which promises much to prevent it ; the em- 

 bryonic shells have been forming, and there is every reason to believe 

 that, could we prevent the initial putrescence and mortality, we could 

 carry them along much further than has yet been done. The tempera- 

 ture of the water has varied from 76o F. to 85° F. to-day. 



July 20. — The embryos are hard to find this morning in the jars con- 

 taining the lots of July 17 and 18, although the men employed in filter- 

 ing off the water and renewing it have worked most conscientiously 

 both night and day. Amceba proteus I find to be abundant in the sedi- 

 S. Mis. 46 49 



