MUSEUM OF COMPARATIVE ZOOLOGY. 93 



APPENDIX. 

 On an Apparatus for the Care and Hatching of Fresh-tvater Fish Eggs. 



Plate V. is a diagrammatic sketch in section of the apparatus used in 

 caring for trout and sahnon eggs. The arrangement is hardly practi- 

 cable for large quantities of eggs such as are handled in fish hatcheries, 

 but for laboratory and experimental use I have found it to answer all 

 ordinary requirements. 



For operation of the apparatus there is needed a steady supply of tol- 

 erably clean cold water, such as a city hydrant supplies, a cool clean 

 room, and a sipk or water escape. 



As shown by the diagram, the water enters at the faucet A, and, splash- 

 ing on the board B, is thus aerated and falls into a box containing a num- 

 ber of filtering partitions. This box is water-tight, and provided with a 

 set of four flannel filters (C, C). These filters are of different grades of 

 fineness, the coarsest being the one through which the water first passes, 

 and they are stretched across the box by means of movable wooden 

 strips fitting closely into grooves made by nailing pairs of cleats on the 

 three sides of the box, so that they can be changed and washed, or dried 

 and brushed, and used again. All use of metal in the apparatus is 

 avoided except where necessary, and then it is covered by paraffine or 

 other harmless substance. 



The water leaves the filter-box by means of a tube near the top of the 

 box, from which it falls on to another board (E), being thus further 

 aerated as it falls into a rather large dish or trough. Placed in this 

 trough is a bell jar (N), with a considerable opening at the top, and with 

 a piece of cheese-cloth or fine netting stretched and held in place across 

 the bottom of the jar by a rubber band. The jar is raised some distance 

 from the bottom of the trough by means of supports under the sides of 

 the jar. At the further end of the trough from that where the water 

 enters is placed a siphon (F), as seen in the diagram. When the appa- 

 ratus is in running order, the eggs are placed in the bell jar and spread 

 upon the cloth in a single layer. The short end of the siphon is placed 

 in the trough in such a position that its orifice is a little distance above 

 the level of the layer of eggs, so that when the water is siphoned off, as 

 will be explained later, the eggs will not be left out of water. 



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