Farr and Florance. — Influence of Ripples. 



239 



rapidly as the young fry are removed farther from the well-pipe. The yolk- 

 sac develops a bluish portion, and an examination of this shows it to be filled 

 with a fluid, and not with a gas. 



With regard to the mortality amongst the ova, and the blue swelling, 

 some experiments, which were in progress at the time the previous paper 

 was read, have, with the aid of Mr. Rides, of the fish-hatcheries, just been 

 completed. It will be remembered that of 15,000 eggs put in each pair 

 of five sets of boxes, from box to box of which the water rippled and splashed 

 down, the following were the deaths in the egg stage : — 



Box No. 



„ No. 

 „ No. 



„ No. 

 „ No. 



Thus there hatched in — 



Box No. 



„ No. 

 „ No. 

 „ No. 

 „ No. 



and of these numbers 



Box No. 



„ No. 



„ No. 

 „ No. 

 „ No. 



the following developed blue swelling : — 



6,675 

 5,232 

 4,650 

 4,713 

 3,252 



8,325 



9,768 



10,350 



10,287 



11,748 



1,626 

 1,269 

 1,584 

 1,358 

 1,557 



or the following percentages of the fry which were born. The gas con- 

 tent of the first and last, and the radium-emanation content of the series, 

 is given along with these : — • ? i '. 



Percentage of Fish 



developing Blue 



Swelling. 



Gas Content. 



r Nitrogen, 16-82 

 \ Oxygen, 5-34 

 (.Carbon-dioxide, 1-80 



No. 5 



13-0 



r Nitrogen, 15-98 



<. Oxygen, 5-68 



( Carbon-dioxide, 1-88 



Radium 

 ^Emanation. 



126 



111 

 95 

 83 



69 



The acclimatisation authorities assert that the proportion of blue swelling 

 in the top box to that in the bottom is usually much greater than this, and 

 ascribe its comparatively even distribution over the boxes to the fact that, 

 owing to conditions, eggs likely to develop it died before hatching. 



In another series of eight boxes arranged so that the water rippled from 

 box to box, the ratio of blue swelling in box 1 to that in box 8 was as 

 5 to 2. We have no data regarding the gas content or radium-emanation 

 content of this series, but the figures given seem to show that the mortality 

 amongst eggs, the blue swelling, and also tke radiima-emanation and the 

 nitrogen content, fall off, whilst the amount of oxygen slightly increases. 



