[11] FISH CULTURE IN CENTRAL EUROPE. 549 



many of which are set in terra-cotta, and have, in place of the glass 

 beams, beams of chalk. In these tables the water flows over the eggs 

 more easily, and does not flow among them ; the aeration, however, is 

 not and can not be so defective as in the Coste stairway, since the water 

 flowing through pipes from the front edge on to the table below rushes 

 down upon it, and rises again a little, and in every compartment spreads 

 advantageously over a large surface. But it is certain that the renewal 

 of the water must form the proper test, whether apparatus can, in the 

 establishment which possesses it, be used to advantage or not. The 

 Coste tables at ITuuingen show, by their state of preservation and by 

 their dimensions, that they are not so expensive as those found at Velp. 



The spring water at Hiiningen is iu part made to flow through canals 

 of cemented brick-work which are laid in the ground under the hatch- 

 ing hall. They may be compared to veritable brooks, while by their 

 bottom, arranged in long steps ending in perforated cross partitions, 

 they resemble the Coste tables. 



This system of subterranean cauals has one great inconvenience, as it 

 compels the person who places the frames for the eggs in position, or 

 who has anything to do about them, to work kneeling on the pavement. 

 This inconvenience is not found in the hatching tables at Hiiningen and 

 at Velp, as they are placed at a convenient height. The simplest appa- 

 ratus, however, is the large wooden troughs which I saw at Neuhausen 

 and Dachsen. The first of these were constructed according to two 

 identical models, but differing in size. Two and two are placed length- 

 wise by the side of each other ; their edges are about 20 centimeters 

 [8 inches] high; their shape is that of a parallelopiped; they have a par- 

 tition 25 centimeters from the short edge, opposite to which the water 

 enters if their length is 2.G8 meters and their breadth 43 centimeters [106 

 by 17 inches] ; and at a distance of 8 centimeters, if their total length is 

 68 centimeters and their breadth only 22 centimeters [27 by 9 inches.] 

 The eggs are spread on frames of iron and wire, the water, which is kept 

 at a height of 8 centimeters, flows into the. space between the partition 

 and the outer edge through closed pipes, at the end of which there is a 

 metal grating. 



The Dachsen troughs resemble those which I have just described, but 

 here the eggs are placed on a layer of very fine gravel 2 centimeters 

 [f- inch] high, above which there are 3 centimeters of water. This sys • 

 tern of hatching in wooden troughs, the eggs being placed on very fine 

 gravel, is practiced a good deal in America ; and I have also seen it em- 

 ployed at Zurich, but the same result is said to be obtained by placing 

 the eggs on the carbonized bottom of the trough, or on frames of metal 

 wire, of switches, or glass reeds. I would, however, observe in this con- 

 nection that, the general conditions of hatching being the same, which 

 it seems to me is hard to prove, the frames represent an expensive but 

 durable material, and the gravel a comparatively small expense, all the 

 work required being to get it all of a suitable size, and to wash it iu a 

 dilution of mineral acids before using it. If, therefore, it was not more 



