1864.] JOHNS rox on salmon ova. 455 



ova being safely deposited in the beds at Melbourne and Tasmania, 

 we came to the next Ciitical test — viz., the hatching-out, and 

 the rearing of the young fry. The advices we have from Mel- 

 bourne and Tasmania record the appearance of the ova when de- 

 posited, and when the fish were hatched, the last day of hatching, 

 and the number of young fry they have at each place up to the 

 20th June, 1864. It appears at the time the ova were deposited 

 in the hatching-boxes, the formation of the fish in many instances 

 was so far complete that their eyes were plainly visible. This 

 fact led Dr. Ofiicer and other gentlemen of the Acclimatising 

 Society to conclude that, before many days, numbers of the young 

 fry would emerge from the shell. Such, however, was not the case, 

 inasmuch as the first fish was not hatched until the 4th of May, and at 

 Melbourne on the 7th of May. By the 11th as many as forty trout 

 and nine salmon were hatched, the numbers increasing daily. Un- 

 fortunately during the hatching, the mortality of the ova and the 

 fry reached to something like 100 per diem, which decreased as the 

 season grew colder. The last fish, says Dr. Officer, hatched-out 

 on the 8th of June, fifty-four days after the airival at Tasmania, and 

 147 days after the date of impregnation. After this great success, a 

 want of caution, probably from an over-desire to do more than nature 

 will bear, seems to be one of the greatest disorders we have to contend 

 against. The advices down to the 20th June show the ratio of 

 mortality amongst the ova and the young fry to be so great, that the 

 total number of fish, both at Melbourne and Tasmania, does not 

 exceed 3,300. To what cause are we to attribute the fearful mor- 

 tality among the young fish ? Mr. Joul, writing upon the subject, 

 gays, " It is an established fact that salmon and trout ova can be 

 sent to the antipodes, and hatched there ; but as I am not satisfied 

 with only about 3,000 fry being hatched from about 30,000 living 

 healthy ova that were placed in the breeding-ponds in Tasmania, 

 and about 300 from 1,200 healthy ova in Melbourne, I wish to 

 call the attention of Mr. Buckland, Mr. Francis, Mr. Buist. and 

 other artificial breeders, to these numerous deaths of the ova, 

 after having advanced so fiir in hatching as to have the eyes well 

 developed, and when they ought to be considered safe, with the 

 view to elicit from these gentlemen an opinion of the probable 

 causes, and to suggest a remedy. My own experience is that out 

 of 100 healthy ova taken from the moss, which have not been 

 more than 100 days in ice, I can hatch eighty ; and there appears, 

 from what I know of the river-water and climate of Tasmania, no 



