74 



THE PErxIODIC GROWTH OF SCALES IN GADID.E 



The following table gives a summary of the more detailed tables 

 along with other results, with special reference to annual rings and 

 lines of growth. It may serve to bring out some interesting points. 

 The case of the fish with an asterisk, for example, 27'62 cm. in length, 

 deserves notice. This fish only shows the following lines of growth : 

 year I., 13 ; year II., 13 ; year III., 18. 



We have evidently here to deal with a rapidly grown fish, and this 

 fact has expressed itself in the formation of the scale, in the small 

 number of lines of growth for the first and second year. The more 

 intensive the growth the smaller the number of the lines of growth. 

 To compare with this we might take the case of a slower growing 

 pollack, 44'40 cm. The scale of such a pollack shows the following 

 lines: year I., 21 ; year II., 29; year III., 18 ; year IV., 2. It is pro- 

 bable that in the first case the fish grew quickly in years I. and II., and 

 in year III. about the normal. 



SUMMAKY OF EXAMI:N"ATI0N OF POLLACK SCALES, 

 With Special Reference to the Annual Rings and Lines of Growth. 



Average number of lines of growth 



(excentric lines) in years. 

 1 23456789 



- • 



2 - ■ 



2 - 

 2-3 - ■ 



4 - ■ 



3 - - 



5 - ■ 

 5 - ■ 



16 - ■ 

 not taken ■ 



15 - - 

 14 - - 

 14 - - 



14 - ■ 

 21 - ■ 



not taken ■ 



20 - ■ 



18 - - 



not taken - 



17 - - 



16 - - 

 16 - ■ 

 16 - ■ 



15 - - 



16 - - 

 15 - - 

 15 - - 



18 - - 

 not taken - 



20 - - 



20 - - 



18 4 - 



Notes. 



„ 6 



„ 6 



„ 8 



„ 8 



J,, 8 



§„ 8 



t See PI. I., Fig. 1. 



See PI. I., Fig. 3. § See PI. I., Fig. 2. 



