420 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ins: of the esrsrs and the return of the fish to the breeding- 



o o O cj 



ground, at which time it has attained a weight of from five 

 to eight pounds. The number actually taken at Hameln, 

 however, is no criterion of the yield, since scarcely more than 

 one third ascend as high as that point, the remainder finding 

 satisfactory breeding-places in the shallow gravel beds below. 

 When the temperature of the water exceeded 60, the sal- 

 mon appeared to be exhausted, and unable to continue their 

 active efforts at ascending the river, and waited for the cool- 

 ing of the w T ater either by a change of external temperature 

 or by a rise from the upper springs. D. Fischer ei~Verein y 

 1872 ; Circular 8, 192. . 



TROUT- BREEDING IX FRANCE. 



In the London Field is a suggestive article upon fish- cul- 

 ture, in the form of an account of the trout-breeding establish- 

 ment, near Rouen, of the Marquis De Folleville, a gentleman 

 whose success in raising this excellent fish has long been well 

 known. He bears testimony to the importance in fish cul- 

 ture of not attempting to keep the fry confined in small 

 spaces for a long time. It took him five years to reach this 

 conclusion. Finally, having become discouraged in his ef- 

 forts, he undertook to let out the fish into the stream shortly 

 before the time for the absorption of the yolk-bag, and 

 obliged them to seek food for themselves. The result was a 

 complete success, the weeds furnishing protection for the fish, 

 and supplying them with such a number of minute insects 

 that they attained the length of four or five inches the first 

 year. 



At the present time, streams on his estate which ten years 

 ago produced nothing, now yield a return of from $900 to 

 $1200 per annum, which is double the production from the 

 same acreage of the most fertile land in France. In the es- 

 tablishment of the marquis, the eggs, after having been fer- 

 tilized, are deposited for the first three weeks in a runlet, or 

 trench, twenty feet long, two feet wide, and half a foot deep, 

 through which a flow of fresh spring water is directed. They 

 are then placed in a close hatching-box, in which they are 

 kept until the yolk-bag is absorbed, after which they are 

 turned out into the stream, and thenceforward require no 

 special care. 



