[3] CALIFORNIA SALMON IN THE NETHERLANDS. 711 



Amsterdam via Bremen. This time the minister, at my suggestion, 

 offered to bear all the expenses, to be paid from the treasury of his de- 

 partment, leaving the whole matter entirely in my hands. 



When, on the 26th of October, the eggs were placed in the gardens of 

 the Zoological Society, where they were to be hatched, 82,600 out of the 

 85,000 which had been received were found to be in good condition. 

 Of these 19,497, or 24 per cent., perished during the incubation. This 

 was probably caused by the high temperature of the water during the 

 hatching process ; it i s also possible that in unpacking the eggs I did not 

 change the temperature gradually enough. Eaising the temperature too 

 quickly and letting it remain high is very apt to prove injurious to the 

 eggs. When hatched, many of the little fish did not seem to possess 

 the necessary strength to get free of the egg-shell when it burst, and in 

 their attempts to do so some of them were choked. 



Through the good care which was taken of the young fish in the gar- 

 dens of the Zoological Society, about 61,000 young salmon were suc- 

 cessfully hatched, whose umbilical bag had almost entirely disappeared. 

 Although there was no precedent that salmons younger than one year 

 had been set out in rivers, 50,000 of these fish had, nevertheless, to be 

 set out in the river Meuse, near Venlo, in January, 1879, as the Zoologi- 

 cal Society needed all the space at their command for the hatching of 

 Ehine salmon. 



In spite of the very unfavorable weather, as there was a hard frost, 

 we succeeded in preventing the freezing of the water in the cans in 

 Which the fish were transported, principally through the very valuable 

 aid extended by the superintendents of the railroad stations at Amster- 

 dam, Utrecht, Boxtel, and Yinlo. Although the journey — and, therefore, 

 the stay of fish in the cans — lasted about eight hours, the loss was trifling. 

 With the same success 5,000 young salmon were set out in the Zwaans- 

 prong, near Apeldoorn, and about the same number in the small streams 

 which feed the Molecate ponds near Hattem, to which the owner, Baron 

 van Heeckeren van Molecate, kindly gave his consent. The object was 

 to have an opportunity of observing the development of the young fish 

 when in a free condition. In spite of all precautions it seems that the 

 young fish escaped from Molecate ; and although every effort was made 

 to track them, they could not be found. 



In the Zwaansprong we were more successful. It is true that their 

 number decreased through cannibalism ; but this is a common occur- 

 rence with fish of prey when — as in this case purposely — they are not 

 fed. A considerable number, however, were l©st by the breaking of a 

 dike, the fish escaping through the opening into the Diereusche Canal. 

 As the break in the dike was fortunately soon discovered, about 1,400 of 

 the deserters were caught and placed in one of the ponds of the neigh- 

 boring establishment of Mr. Nordhock Hegt. As early as October, 1879, 

 I found young salmon measuring 13£ centimeters. Of those which had 

 been set out in the Meuse many were observed during the first few days 



