As seen from this table, wire-mesh frames s^ive the best results and the space for the 

 passar;e of v;ater obviously determines the final results. The relatively good results 

 obtained from wooden frames are onl;"^ due to the small nurriber of ezcs per frame. On account 

 of this, each e^g rested automatically upon a slit, that is, v.'as directly in touch vrith the 

 water current. In order to avoid any eventual blocking of the v;ater current the breeder 

 should not make use of especially reinforced frames, whiile in order to avoid "air pockets", 

 the meshes should be bossed somewhat downward. This will not interfere with the eggs. 

 The troughs can be made of either wood or white metal. Industrial manufacture, like in 

 the long stream apparatus, is not customary on account of the small demand. 



The "long stream" apparatus consists of a long trough of at least 1,50 meter in length. 

 Material as well as width vary according to conditions. For smaller hatcheries wooden 

 troughs (Fig. 26) are recommended, v;hile large breeding plants will mostly use stone or 

 cement troughs. The frames ("boats", "cradles") are simply set into these troughs, some- 

 tiiaes even in layers, one on top of the other, and must be wide enough to completely fill 

 the trough, somewhat above the v/ater level. 



This arrangement forces the water to flovi through the transverse sides of the frames. 

 All interference vdth a free current is scrupulously to be avoided. The "boats" had best 

 be formed as shown in Fig. 26, the feet are made of tin. The suspension of the sieves 

 froni a l-.ijher edge or setting them on points in the side walls is impractical. All that 

 was said with regard to "under current" apparatus is also to be taken into consideration 

 here, 



A ?reat advantage of the "long stream" apparatus is that it requires only a low 

 degree of inclination, and secondly, very important, after removal of the "boats", the 

 spaciousness allov;s its use for brood feeding. 



In order to avoid an eventual escape of the fry, the transverse wails sliould be 

 raised by frame screens (wood frames holding sheet metal vdth 2 mn. perforations setting 

 in slots in the side walls). The lower frame, if placed somevfhat slanting will act as 

 an automatic stream cleanser. 



I estimate the minimum of necessary inflow — ^T.'hen using California baskets — at O.J* 

 liter per second and per square meter of egg resting place. The frames can be stocked 

 with two layers of eg^s in any of these apparatus. Jiore than two layers are not advis- 

 able on account of the excretion factor mentioned earlier in this book. Trout eggs of 

 5 milli.-iieters in diameter can be placed up to four per square centimeter in one layer 

 and up to eight v;hen stocking the frames with tv/o layers per frame. From these figures 

 the required dimensions can easily be determined in case of new installations. 



60cm 



•^*^^ 



^^^rnrrrrT^ 



300cm 



Fig. 26. Long-stream Apparatus for the Incxibation of Trout Eg-s. 

 Only one of the four sieve insets is drawn. The framed screens at the 

 inflow and outflow are set in place only when the box is to be used for 

 feeding the brood. The water level is regulated by a small sluice board. 

 Covers are placed on during incubation. 



111 



