474 Transactions.— Miscellaneous. 
78 days, which is very nearly the same as an average of all the days from 
1878 to 1882, including these abnormal numbers. Among the 1880 ova, 
the lot which took 95 days to hatch are thus referred to by Mr. Deans, the 
local society's manager :— They were impregnated on July 27th, and on 
October 30th I preserved a few eggs, which were still unhatched ;” while 
his note on the other abnormal case in 1881 is this :— Boxes 9 and 12 
impregnated August 17th, hatched out on October 20th, 64 days.” The 
first of the season’s ova were impregnated July 12th, 1881, from which date 
to August 17th, the water in the hatching-boxes showed an average of 48° 
by Fah. thermometer; while from August 17th to October 20th, the 
thermal readings, I have gone carefully over, and find that they also give 
an average of 43° exactly; so we may conclude that the temperature of the 
water had nothing whatever to do with the rapidity of this particular hatch- 
ing. Much more complete observations would have been required than 
have ever been kept, to detect the real reason of this, but the parent fish of 
this 64 days’ lot were late spawners. Mr. Deans has found that 14° Fah. 
difference of temperature makes 10 days’ difference in the time of hatching 
at Opoho in the creek water. à 
It is of interest to compare the time of development from impregnation 
to hatching in England with the above. Ina report on the Cray Fishery, 
Kent, I find the time given at from 70 to 84 days,* practically the same as 
our experience in Otago has proved it to be. But this does not show what 
the time has been in other English hatcheries, and is much longer than 
that given by Yarrell as the result of an experiment in Germany, where it 
was found to be only 35 days. We find, however, that temperature affects 
the time very much, and probably late spawners too. Among all the autho- 
rities on fish within my reach, there are but two others who make mention 
of the period of trout hatching, viz., Rev. W. Houghton, in ** British Fresh 
Water Fishes," 1879, where he gives it as 60 days, and the temperature 
40° to 45°; and Mr. Francis Francis, in the “ Practical Management of 
Fisheries,” 1883, where 68 days is, as nearly as I can make out, the mean 
time recorded. From the above cases, it would seem that the average 
duration in Europe is somewhat shorter than in Otago by about three 
weeks, but whether this is corroborated by the experience of fish-culturists 
generally at Home is more than can be readily found out. The three Eng- 
lish examples quoted, however, show a mean of 67 days, or 10 days shorter 
than we have it here; and there is no alteration in the time observable 
during the past five years in our Opoho hatching-boxes, from what it was 
prior to 1878. But our trout can only properly be compared with their 
* “Illustrated Sporting and Dramatic News,” February 24th, 1883. 
