BIRTH, GROWTH AND REPRODUCTION OF OYSTERS. 105 



without operating with the oyster-knife, is to place oysters 

 newly dredged in the sun ; they will shortly ' gape their 

 shells,' and then, by peeping carefully in between the 

 shells one can see in those which contain spat a mass of 

 mud-like material adhering round the beard of the oyster. 

 If the embryo be nearly ready to be emitted from the 

 parent shell, it much resembles slate pencil in a state of 

 powder ; if it be in a less advanced stage of maturity, it is 

 of a white, milk-like colour. It has been stated that from 

 one to two million young oysters are produced from a 

 single parent. I have examined several native oysters of 

 the average size and weight, and never found the highest 

 number of spat to be more than 829,655, and the lowest 

 2 7 6,555- Even with these reduced figures, imagine what 

 an enormous number of young ones must be produced 

 from the parent oysters in a well-stocked laying or oyster 

 bed ; and yet the 'fall of spat' for the last five years has 

 been bad in other words, although the young oysters 

 have been born, something has happened to them, and 

 they have died in their infancy." 



the young fixed oysters, on the other ; while there is no familiar name 

 for the very important stage of development which lies between these 

 two. 'Brood,' 'fry,' and 'spat' would be very convenient names 

 for the three stages, if ' brood ' were not already in use for the smallest 

 of the young fixed oysters. Perhaps the most convenient course will be 

 to use ' fry ' for the eggs or embryos which are contained within the 

 mantle cavity of the parent ; ' larvae ' for the locomotive stage, and 

 ' spat ' for the final condition. In order to become spat, the larva 

 appears invariably to fix itself by one side (almost always the left) ; 

 and, if the surface is favourable, the extent of the surface of adhesion 

 becomes very considerable, and the oyster is fixed throughout life. 

 But, if the surface of adhesion is small, the oyster, as it increases in 

 size, readily becomes detached and lies free, though motionless, on the 

 bottom." Professor Huxley, " Oysters and the Oyster Question." 



