[9] ARTIFICIAL PROPAGATION OF FISH. 499 
one ought to endeaver to confine the crossings to their reasonable 
limits, and to repeat them through several generations, always cross- 
ing the primitive kind with cross-breeds. 
CHAPTER II. 
HATCHING APPARATUS. 
After the eggs have become fecundated they are placed in the hatch- 
ing apparatus. For this purpose perforated boxes, resembling sieves, 
baskets of different shapes, boxes of wood, stone, earth, metal; sieves 
of every kind &c., have been proposed, and the only trouble is which 
to select among so many different kinds. 
The long, open boxes described by Jacobi have for a long time been 
successfully employed in Germany, and have been replaced by the cir- 
cular boxes of tinned iron, perforated like sieves, of Messrs. Gehin 
and Remy, which are still used in Germany, owing to the high praise 
bestowed upon them by Dr. Fraas, of Munich. He explains his prefer- 
ence for the apparatus of the two fishermen of La Bresse by stating 
the inconveniences presented by wire sieves, which easily rust and favor 
the generation of parasitical conferve. Zhe experience of allages, 
however, has demonstrated that perforated boxes can only be success- 
fully employed in very pure running water, as the holes easily become 
stopped up and are rendered useless by the oxidation of the tin of 
which they are made. The open wicker baskets recommend themselves 
by their cheapness, but they offer too little resistance to the enemies of 
the spawn; boxes made of coarse hair present the same inconveniences 
without even the advantage of being cheap. 
These considerations have induced Mr. Coste* to find some method 
which would always enable him, whenever he deemed it useful, to 
manipulate the products inclosed in his apparatus and to pass them 
from the hatching-brooks to the fish-ponds. The incubating apparatus, 
consisting of artificial streams of continually-running water, were the 
result of Mr. Coste’s researches. Their simplicity and their evident 
usefulness were immediately recognized, and facilitated the adoption of 
this system in a more or less modified form. We will first describe the 
apparatus in use in the piscicultural establishments in the Nether- 
lands. ; 
At the bottom of a common spring, with a capacity of 30 to 35 liters, 
beds are prepared of gravel, sand, and charcoal, The water, after hav- 
ing passed through the filter, flows through a faucet into a wooden 
tank, clothed on the inside with zine or lead (a vessel of glazed clay is 
preferable) ; at the end of this tank there is an opening through which 
the water flows out into a small pond or tank. 
The fecundated eggs are placed on hair frames and immersed in the 
*CosTE : Comptes-Rendus, pp. 43 and 46. 
