474 Transactions. — Miscellaneous. 



78 clays, which is very nearly the same as an average of all the clays 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 wore 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, G4 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 43° 

 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 1^-° Fah. 

 difference of temperature makes 10 days' difference in the time of hatching 

 at Opoho in the creek water. 



It is of interest to compare the time of development from impregnation 

 to hatching in England with the above. In a 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., Kev. W. Houghton, in " British Fresh 

 Water Fishes," 1879, where he gives it as GO days, and the temperature 

 40° to 45° ; and Mr. Francis Francis, in the " Practical Management of 

 Fisheries," 1883, where 63 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. 



