[11] OYSTER-CULTURE AT THE LONDON EXHIBITION. 923 



piles, each containing about twenty bricks. In that case they are held 

 together by a galvanized-iron wire, which is passed through a couple of 

 holes in each brick and tied into a knot at the top, by mea»ns of which 

 the bricks are laid and taken up again. 



The collectors are left in the water till September, when the small 

 vessels again come to the beds and remove them to the pares, where 

 they are kept during the winter. In April the young oysters are taken 

 ofi" the collectors by means of axes with a semi-circular blade, a small 

 groove being made in the lime all round the oyster, which is removed 

 by a pressure from the side. The young oysters are then placed in the 

 so called "hospitals," where they are kept until they have reached the 

 length of 3 or 4 centimeters, when they are removed to the deeper beds, 

 where they remain till they are ready for the market, generally for two 

 or three years. In spite of the practical manner in which the Dutch 

 manage all their business, and in spite of the utmost care, the oflBcial 

 Dutch reports state that 80 per cent of the young oysters are lost be- 

 fore they have reached a salable size ; 10 per cent are lost in the pares, 

 40 per cent in the " hospitals," and 30 per cent on the beds. The oys- 

 ters are taken from the beds by small vessels, by means of bottom - 

 scrapers of the same shape as those used in England. During this op- 

 eration a war of extermination is of course waged against all enemies 

 of the oyster. 



In the Netherlands science goes hand in hand with practice, and it 

 must be acknowledged that the results of this cooperation are truly as- 

 tonishing, and that in many respects it deserves to be imitated in other 

 countries. The traveling zoological station, which this year was lo- 

 cated at Tholen, has done a great work by solving many problems 

 hitherto considered insolvable, and by correcting many errors. During 

 my stay in the Netherlands five young, energetic Dutch scientists were 

 engaged at this station, which is in operation all through the summer 

 until September. I was received by these men with the greatest kind- 

 ness, and was thus enabled to get an insight into the work performed 

 at the station, and observe their scientific and practical exi^eriments. 

 This year's experiments were made with young oysters in inclosed basins. 

 A firm in Tholen for this purpose placed a large pare at the disposal of 

 the station. By a close board fence the pare had been divided into two 

 parts. Mother oysters and collectors of every kind were placed in 

 both, and in order to supply the water with the necessary amount of 

 oxygen one division of the pare was furnished with a net- work of tin 

 tubes, through which the water was impregnated with compressed air. 

 Into the other division oxygen was introduced by means of long axles 

 to which a number of shovels were attached, and which were constantly 

 kept in rotary motion by a steam-engine. When I left the Netherlands 

 no results had as yet been obtained, but I hope to be able to com- 

 municate some at some future time. The station is supplied with ex- 

 perimental aquariums, scientific instruments of every kind, and a large 

 library. 



