304 BULLETIN OF THE BUREAU OF FISHERIES 



by a relatively weak growth of the scales, whereas afterwards the slower growth of 

 the herring is accoinpained by a relatively stronger increase in the scales. * * * 

 Broadly speaking, the growth of the fish proves to be relatively stronger during the 

 earlier years, that of the scales relatively stronger during the later." In this connec- 

 tion Molander does not explain the overlapping of scales. As was pomted out by 

 Taylor (1916), scales that do not overlap at first must grow proportionately more 

 rapidly than the body in order to do so. 



3. The growth of both the scale and body is undulating — that is, a period of 

 relatively strong growth is followed by one of relatively weak growth or, vice versa, 

 weak and strong growths alternate; but alternating growths in fish and scales do not 

 quite correspond. In the first four years fish and scale growth vary in the same way, 

 but after that it appears that when scales have a strong growth the fish has a weak 

 growth, and vice versa. This " antichronizing undulating growth" heightens the 

 disproportion between the growths of the fish and scales, which is chiefly due to the 

 late formation of scales. Tardy scale formation is also responsible for the lack of 

 synchronism in the imdulating growth. 



4. Lea's explanation of Lee's "phenomenon " (selection and retardation of growth 

 due to sexual maturation; see p. 302) is open to certain objections. If Lea's con- 

 jectures are correct, samples of herring should be predominantly mature or immature, 

 and the lowering of increment values should end with the maturing of the species. 

 But neither of these expectations materialize m the Swedish races of herring. Lee's 



"phenomenon" is due chiefly to the variability of the body-scale \y) ratio from year 



to year, and the fault of the scale method is that it can not follow these changes 

 in any particular age group. Another factor that produces irregularities in calcu- 

 lated growths is the admixture, m varying proportions, in each age group of different 

 growth groups (faster or slower growing fish) that have dissimilar scale growths. 



5. Uncorrected increments of growth and increments corrected for late scale 

 formation were compared with actual measurements from fish. The uncorrected 

 values were always too low in the first year of life (except in age group I), too high in 

 the second and third years, too low in the fourth year, and alternately too high and 

 too low thereafter up to and mcluding the ninth year. The corrected values were 

 much too high m the first year, too low in the second year, on the whole too high in 

 the third year, and thereafter alternately too low and too high including the ninth 

 year. The alternation of high and low calculated increments is due to the undulating 

 growth of the scales. 



Huntsman (1918a), employing four species of fish, made measurements of four 

 scale dimensions and examined scales from six different body areas. He measured 

 the dorso ventral or transverse (F) diameter, the anteroposterior or long ( W) diameter, 

 and the anteroposterior dimension of the anterior {X) and posterior (F) fields. The 



total length of the fish {L) was used as a standard. In Clupea harengus y decreases 

 continuously with the increasing length of fish, ^ decreases with growth at first rapidly 

 but later extremely slowly, while ^ decreases rapidly at first, then more slowly, 



