296 



Part III. — Twenty-fourth Annual Report 



but the great bulk of them had at this time a length of 25mm. to 

 28mm. (1-1 J inches) ; they could not be older than three months, showing 

 a rate of growth of at least 13mm. a month, while the majority could 

 scarcely be older than six weeks. By the end of July they were trans- 

 formed, and then measured 45mm. to 55mm. (1J-2 T 3 ^ inches). 



It is important in considering these results to note the temperature 

 prevailing in the locality, and I append here a table compiled from those 

 in Meyer's paper, for the ten months given ; up to and including July 

 they refer to Schliewasser, and are the mean of three years, 1875-77 ; 

 for the rest they refer to Kiel Bay and are the mean of two years, 

 1375-76. They are all surface temperatures, and are in F. 





Mean. 



Maximum. 



Minimum. 



March, 



35-6 



41-9 



320 



April, 



442 



50-0 



39-2 



May, 



51-2 



57-2 



42-8 



June, 



62-2 



70-9 



518 



July, .. 



66-2 



723 



57-2 



August, 



67-1 



72-7 



58-1 



September, 



615 



66-9 



52-5 



October, 



54-5 



59-7 



44-2 



November, 



43-3 



50-7 



349 



December, 



36-9 



442 



32-9 



On 11th June, 1874, Meyer put into a floating box at Kiel a number 

 (not stated) of transparent post-larval herrings, measuring 25mm. to 

 28mm., the growth of which is shown as follows : — 



Date. 



No. of Days. 



Length. 



Increase. 



Mean Approximate 

 Growth per Day. 







Mm. 



Mm. 



Mm. 



June 24, 



13 



31-33 



4-7 



•42 



July 6, 



25 (12) 



37-38 



5-6 



•46 



21, 



40 (15) 



41-43 



4-5 



•30 



August 1, 



50 (10) 



45-46 



3-4 



•35 



The transformation of these spring herrings was completed when they 

 were 41mm. long ; and the total growth in the 50 days was about 

 15mm. to 17mm. of an inch), or about 10mm. a month. 



This experiment was a good one, and it would have been improved if 

 the numbers at the different sizes had been noted. It will be seen that 

 growth became somewhat slower towards the end of the experiment. A 

 growth of about 10mm (§ of an inch) per month at this period, and with 

 high temperatures prevailing, is not perhaps excessive. 



At the end of August and beginning of September, Meyer also 

 measured the young herrings in the neighbouring bays, after they had 

 left the mouth of the Schlei and were mixed with other and larger 



