PART II 



Environment and Culture 



RESUME OF THE STAGES OF DEVELOPMENT 



Periods of Practical Importance. — Having described the origin from 

 the egg and the development up to a size approaching maturity, we are 

 now in position to cast a retrospective glance over the different stages and 

 events and to pick out the especial forms, periods, or conditions which 

 afford opportunities for turning the rapid reproductive and growing powers 

 of the oyster to advantage in furnishing occupation and gain to mankind. 



The most important events or processes in the developmental life of 

 the oyster that afford possible usefulness to man are three: spawning, 

 swarming and spatting. 



Spawning is the natural extrusion of the spawn or eggs from the 

 mother oyster into the sea-water about her. The time at which this occurs 

 has been variously stated by different observers, most of whom have al- 

 lowed a broad latitude to cover differences of place, season, variety, etc. 

 It is also certain that the actual process, on account of the position of 

 oyster beds below water, has been seldom if ever observed. The data for 

 its calculation have been mostly obtained by examining the genital organs 

 of oysters, either from the surface to observe the plumpness, colour, etc., 

 or microscopically to note the size, shape, freedom, and structure of the 

 eggs. This presupposes a certain expert knowledge and ability, which 

 few people possess, and which can only be acquired by considerable ex- 

 perience and good judgment. It is an easy matter for a man who has 

 studied other animals to make a mistake on the oytser. It is advisable 

 that he should examine a large number from different beds and at dif- 

 ferent times before, near to, and after spawning as a preparation. To 

 make sure that eggs are ripe it may be necessary to fertilize them and ob- 

 serve that they can develop. It will usually be sufficient, however, to ob- 

 serve that they flow easily from the genital opening when a slight pressure 

 is applied. When the determination of the time of spawning is important 

 it will be best to examine it for the place and season concerned, and to ex- 

 tend the examination to a large number of individuals taken from different 

 parts of the area. A few specimens from a convenient shallow-water bed 

 is not a safe indication of the condition of the masses. 



On account of great differences between European and American 

 oysters it is not safe to judge from analogies. The English or common 



