[37] 



FISH CULTURE IN CENTRAL EUROPE. 575 



vessels for measuring" the eggs ; California boxes, whole and in sec- 

 tions, cans for transporting eggs, etc. 



In these short courses apparatus, fish, and eggs are shown, while in 

 a small room of the academy, which has been transformed into a batch- 

 ing chamber, the California apparatus is shown in full operation with 

 trout eggs. 



Analysis of lectures on the artificial raising of trout 



A. 



I.— Introduction. Propagation of trout in open waters. 



1. Waters in which trout and their kind live. 



2. The spawning of trout in open waters: 



a. The spawning season (winter), and the spawning places. 



o. Fecundation of the eggs laid by the female by means of milt ejected by the 



male. 

 c. Dangers to which the eggs are exposed daring their development and dining 



the hatching. 



3. Showing that in open waters only a small percentage of the eggs is hatched. 



Can this be remedied by artificial raising ? 



II. — The artificial raising of trout. 



1. Idea of artificial trout raising, i.e., an artificial way of depositing, keeping, and 



hatching the eggs and protecting them against dangerous influences. 



2. Method of artificial fecundation : 



a. The procuring of spawning fish. 



b. Separation and distinction of the sexes. 



c. Indications of sexual maturity. 



d. The spawning of the ripe female. 



e. Dry fecundation of the eggs by means of the milt. 



/. Counting the eggs by means of a measuring glass, and their introduction into 

 the hatching troughs. 



3. Necessary conditions for the development of fecundated eggs. Precautions to 



prevent any animals from destroying the eggs. Pure water needed inces- 

 santly : 



a. By chemical processes the water should be kept free from injurious matter. 



b. And by mechanical processes from mud. 



c. Its temperature should not be too high (0.5° to 8.6° C.) [33° to 47.5° F.]. 



d. The largest possible quantity of air should pass through the water. 



e. During the hatching time it should neither cease to run nor freeze. 



4. The California box, the apparatus best adapted to raising a small quantity of 



trout : 



a. Description and demonstration of the California box and its accessory, appa- 



ratus. 



b. Instructions for placing it in position. 



c. Demonstration of the advantage of the California boxes, as compared with 



other apparatus, where the eggs are placed on a bed of sand. The advant- 

 ages consist in a saving of space, and in the greater ease with which the eggs 

 and young fish are kept clean. 



5. Care of the eggs during the hatching time : 



a. They should be left entirely undisturbed during the first week. 



b. Dead eggs should be removed every day to jirevent the formation of fungus. 



c. All sediment should be removed. 



6. Young fish, and their care : 



a. The approach of the hatching is indicated by the visibility of the eyes of the 



embryos. 



b. The young trout is hatched with an umbilical sac. 



c. Change of the young fry to a small fisb. 



d. Keeping the young fash clean, and regularly removing the dead. 



7. Placing of the young fish in water adapted to their raising : 



a. The proper time for placing the fisb in water. 



b. Hatching brooks and hatching ponds. 



c. Transportation of the young fish to the w r ater ; cans employed for transporting 



them. 



