776 



BULLETIN OF THE BUREAU OF FISHERIES. 



From the time of hatching to the transference of the fry to another car 

 specimens were taken out daily and preserved. The average daily measure- 

 ments are here given : 



July 26 3.85 



July 27 4.85 



July 29 . 5.82 



July 31 6.21 



August I 6. 90 



August 2 7.19 



Augusts 7.68 



Mm. 



August 4 7.90 



Augusts 7.70 



August 6 7.76 



August 7 8.32 



August 8 8. 00 



August 9 7.98 



August 10 8.23 



August II 8 



August 12 8 



August 13 9 



August 14 8 



August 15 9 



Mm. 

 ", 22 



80 

 20 



77 

 30 



On the afternoon of July 27 a portion of the eggs which had remained 

 unhatched in the experiment thus described were transferred to another simi- 

 larly rigged rearing car (known as S 4) , and these eggs hatched within the next 

 day or two. The measurements of specimens taken daily from this new car com- 

 pare in an interesting way with those given in the previous table. Although they 

 came from the same batch of eggs, and differed only in being slightly younger, 

 they grew more rapidly than the first lot and soon so far outstripped those in 

 the original car that the difference was noticeable upon casual observation. 



This difference was doubtless due to the fact that the second lot had more 

 to eat because there were fewer specimens in the car, for, as we have said, the 

 fry had to depend for their food upon the pelagic fauna. By towing in these 

 cars with a small bolting cloth net the absence of copepods and larval animals 

 was conspicuous, especially when compared with the towings taken from a neigh- 

 boring control car which was in all respects similarly conditioned except that it 

 supported no young fishes. In the latter the pelagic life was abundant. It 

 was evident that the swarm of young fry used up the supply of pelagic food as 

 fast as it came into the car. 



The following table gives the daily average length of specimens of Menidia 

 in this second experiment: 



July 27 4 



July 28 4 



July29 -.-. 5 



July30 '- 6 



July3i-- 5 



August I 6 



August 2 7 



Mm. 



52 



Augusts 7- 76 



August 4 8.72 



August 5 9. 00 



August 6 _ 9.98 



August 7 9.82 



August 8 10. 02 



August 9 -- 9.25 



August 10 10.04 



August II lo- 34 



August 12 10.12 



August 13 lo- 74 



August 14 10.21 



August 15 11.72 



August 17 - 10.26 



The regular measurements were discontinued after this date. On Sep- 

 tember 8 the average measurement was 14.83 millimeters and on September 141 

 14.45 millimeters. In all of these measurements different groups of individuals 

 were caught up, and the averages, therefore, seem to show a decrease in size 

 rather than an increase when there is not considerable rapidity of growth. 



