242 KNUT DAHL. 



cases still suffering from the saprolegnia some were reconvale- 

 scent and some were healthy. 



During the first days after the transfer to saltwater (about 

 10 ^/oo, gradually increasing to 33 *^/oo salinity) ca. 30 died. 

 However the 40 fishes, which were left, got on very well. 



They were fed partly on worms, partly on gammarids. 

 Later on during summer their main food was the young of 

 GoMus Ruthensparri of which quarts of Hving specimens might 

 be taken in every haul with a small seine of mosquitonetting. A 

 supply of living food was thus constantly kept in the aquarium 

 with the fishes, who might eat as often as they liked. 



Through autumn, when this source of supply ceased, chopped 

 fresh herring or herring roe was used. 



Their appetite however stagnated during winter with the 

 sinking temperature. Only a few casualties occurred during 

 summer and autumn, but the months after christmas 1900 de- 

 manded about 55 victims. In spring 1901 when their appetite 

 again began to assert itself only 15 were left. 



As will be understood it has not been possible directly to 

 measure their growth during this period but it was evident, 

 that they did not grow anything worth mentioning during the 

 winter months. 



During the first summer however they grew very rapidly. 

 None of them measured more than 13 cm. when they were 

 transferred to the saltwater aquarium. In autumn the largest 

 were nearly 20 cm. long. 



During the second summer their growth was very rapid 

 and they increased enormously in bulk. 



The fishes were killed off on October 18, 1901 and were 

 measured öfter having been kept a few days in a preserving 

 fluid consisting of water, spirits of wine and formalin. 



The measurements ran as fellows: 



