OYSTERS AND METHODS OF OYSTER-CULTURE. 335 



to 1)6 covered by too large a number of spermatozoa; thousands more than are 

 required if too much is used. These superfluous spermatozoa simjily become the 

 cause of a putrescent action, which is injurious to the healthy development of the 

 eggs. A drop of milt to 20 drops of eggs is quite sufficient. 



Immediately after the ova have been fertilized it is best to put them into clean 

 sea water at once, using water of the same density as that in which the adults grew. 

 If the attem])t is made to impregnate the eggs in water much denser than that in 

 which the adults lived, it is probable that the milt will be killed at once. This 

 singular fact, which was accidentally discovered by Colonel McDonald and myself, 

 shows how very careful we should be to take into consideration every variation in the 

 conditions aftecting a biological experiment. If sufficient water is used no trouble 

 will be experienced from the pollution of the water by dangerous micro-organisms, 

 which are able to destroy the oyster embryos. From 50 to 200 volumes of fresh, 

 clean water may be added to the volume in which the eggs were first fertilized. 

 This may be added gradually during the first twenty-four hours, so as to assist 

 aeration and prevent the suffocation of the embryos. * 



ARTIFICIAL FEEDING. 



There is no practical way now known of furnisliing oysters witli an 

 artificial food supply. 



Experiments have been made with a view to feeding the adult oysters 

 upon corn-meal or some similar substance, but such attempts have been 

 of no practical value. There is no doubt that they would eat corn-meal 

 or any other substance in a sufficiently fine state of division to be acted 

 upon by the cilia. The oyster is incapable of making a selection of its 

 food, and probably any substance, nutritious, inert, or injurious, would 

 be swept into the mouth with complete indifference except as to the 

 result. Corn-meal and similar substances would doubtless be nutri- 

 tious, but their use must be so wasteful that the value of the meal 

 would be greater than that of the oyster produced. 



The only way in which the amount of oyster food can be increased is 

 by so regulating the conditions in ponds or parks that the natural food 

 may grow in greater luxuriance. In artificial propagation the life of 

 the young has been prolonged beyond the early embryonic stages by 

 feeding upon certain marine algie reduced to a powder by pounding 

 them in a mortar, but such successes have been purely experimental 

 and are of no significance from a practical standpoint. Even if artificial 

 propagation were to obtain a place in practical oyster-culture, the fry 

 would doubtless be liberated before resort to artificial feeding would 

 become necessary. 



* Fisheries Industries, Sec. I, pp. 723, 724, 725. 



