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FISH CULTURE IN CENTRAL EUROPE. 



547 



I must also state that the water may receive some air in the open 

 canals through which it is led iuto the hatching-houses at Hiiningen, 

 Selzenhof,Neuhausen, Dachsen, Zurich, Berneuchen,Michaelstein,Velp, 

 and Apeldooru. This small quantity of air is, however, entirely lacking 

 at Cosmandorf, Wilthen, and Seewiese, where the distributing canals are 

 entirely closed. This remark should not be misunderstood, since the 

 object in view may be fully attained, as the water contains a sufficient 

 quantity of air, either owing to the fact that it is either river or spring- 

 water, or by flowing open for a considerable distance after it has left 

 the spring. 



Hatching apparatus. — The character of the hatching apparatus which 

 I saw in operation to some extent partakes of the nature of the period 

 in which the establishments to which they belong were founded ; but 

 they also reflect the special views and the degree of technical education 

 of their directors. 



It is certain that among the very large number of models of hatching 

 apparatus which I have seen there is not one which could be said to 

 answer the purpose better than the others; but if we take into consid- 

 eration the requisites which they must possess, it will easily be under- 

 stood that these requisites may be obtained in many different ways, and 

 by different means. For the sake of clearness I will enumerate the 

 principal requisites which the hatching apparatus must possess, as fol- 

 lows: 



1. They must furnish a suitable, continuous, regular, and uniform 

 supply of aerated water. 



