FISH CULTURE IN CENTRAL EUROPE. 



541 



[3] 



Establishments supplied from springs led to the hatching house through long open courses, 

 or through ponds and canals. 



Wilthen . . . . 

 Liibbiiiclion 



Michaelstein 

 Velp 



Apeldoorn.., 



A spring rising at tlio distance of ono kilo- 

 meter [about 1094 yards], led into-a basin, 

 and thence to the hatching chamber. 



Thiee springs, ono of which rises close to the 

 tillage, and the others at a distance of one 

 kilometer, •whose waters, after being united, 

 are, through a canal of 650 feet, led into a 

 pond, whence through another canal of half 

 a kilometer they are led into the hatching 

 chambers. 



Distant springs furnish water to some ponds, 

 from one of which the water is led to the 

 hatching chamber. 



A spring at a distance of three-quarters of an 

 hour ; the water is led through open canals 

 to a small pond in view of the establish- 

 ment. 



It is doubtful whether the water comes from 

 a spring, as its quantity is truly exceptional 

 (10,000 cubic meters [about 350,000 cu.feet] 

 per day) ; it comes a distance of three kilo- 

 meters [nearly 2 milesj in open canals. 



°C. °F. 

 Hiirh. 



Establishments which use other water. 



Radolfszell 

 Zurich 



Cosmandorf 

 Berneuchen 



Drinking water of the country 



Drinking water of the citv, drawn from the 

 lake. 



Mill canals coming from the river Rothe 



Mill canals coming from the liver Mietzel. . . 



°C. 



1 



4 



OF. 

 34 

 39 



1. 5-8 35-46 

 0-3 32-37 



°C. 



10 



21.5? 



19 

 25 



°F. 

 50 



71? 



66 



77 



Temperature of the water favorable to hatching. — It is at present almost 

 impossible to soy which of the various temperatures under the influence 

 of which the hatching process is accomplished is absolutely preferable ; 

 but in general it may be stated that, in the cold of winter, a tempera- 

 ture which does not rise much above 10° C. [50° F.] is favorable for sal- 

 monoids ; nevertheless there are facts to show that salmouoids have 

 been successfully hatched both at a much lower and at a much higher 

 temperature (at Torbole in water of 11° (3. [51.8° F.], and at Garda in 

 water of 14° C. [57.2°F.]). But it is certain that the development of 

 the embryo succeeds better if the hatching water has an even tempera- 

 ture than if it exceeds certain limits of heat or cold ; and this condition 

 is more generally found in spring water than in other water. It should 

 be understood, however, that favorable conditions of temperature may 

 also.be found in other than spring water ; and if these conditions do not 

 exist, we have seen fish-cnlturists endeavor to obtain them by mixing 

 waters of different origin, as is done or can be done at Hiiningen, Selz- 

 enhof, and Seewiese; or by having recourse to a stove, which in several 

 places I have seen in the hatching rooms, as an indispensable article of 

 furniture. The objection might be raised that the mixing of spring 

 water with other water, or the substitution of other water, the placing 

 of the hatching chambers in the ground, as is done in some northern 

 countries, and the stoves, have no other object than to ward off the 

 dangers of freezing; but we maybe allowed to suspect that practice 

 employs all these means in order to obtain or to approximate that even- 

 ness of temperature which otherwise could not be obtained. 



