OYSTER CULTURE IN HOLLAND. 705 



The investigations concerning the oyster questions 

 which were carried out by means of the transportable 

 Zoological station, and which have just been alluded to, 

 also extend in other directions. The anatomy of the oyster 

 has been carefully inquired into by Dr. Hoek, and I have 

 before me his elaborate treatise with numerous illustrations. 

 The embryology of the oyster has been investigated by Dr. 

 Horst, who is still continuing the researches, part of which 

 are already published. The physical circumstances are 

 similarly inquired into, and series of observations concern- 

 ing temperature and salinity of the water are repeated three 

 times a day at different points of the Schelde. 



In the course of this summer our attention will be more 

 especially directed to the process of fixation of the larvae 

 when, at the end of their free life, they settle down on 

 some hard substance where to develop into a full-grown 

 oyster. To get hold of the largest number of young 

 oysters, fixed in this way to transportable apparatus, is a 

 most important object to all oyster-culturists, and this 

 problem is before them once every year at the breeding 

 season. All the different forms and shapes of collecting 

 apparatus, some of which are here on the table, and which 

 you will find in great variety in the different departments of 

 this Exhibition, tend to the same object. Still the process 

 of being obliged to bring these out into the open sea, 

 hoping that the invisible spat may fix down upon them in 

 great quantities, may to a certain extent be compared to a 

 man trying to catch birds by throwing his hat at a passing 

 flock. 



In order to bring this matter within the reach of man's 

 voluntary interference, different attempts have been' made 

 to let the oyster give off its spat in an enclosed space, 



where it might be collected at leisure on the apparatus 



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