second molt. In both sexes the count rises 

 steadily, more sharply at first, during the 

 adolescent and subadult years. In the full- 

 grown male the maximum count is 68 per 

 bundle; in the full-grown female, 51. 



Quadratic equations fit the data of table 10 

 more closely (table 11 and figure 7) than do 

 linear equations. From figure 8 it will be seen 

 that the regression curves of fiber count on 

 age are similar for both sexes up to age 5. 

 After age 5 they diverge slightly. The number 

 of fibers per bundle continues to increase 

 until 12 years of age in the male and 10 years 



in the female. Quadratic equations cannot be 

 used to extrapolate to older age classes. If 

 the sample had included more old animals, an 

 exponential curve would perhaps have provided 

 a better fit for data throughout the entire life 

 span of the seal. 



It is important to note that the fiber counts 

 of table 10 are arranged by age of seal and not 

 by age of pelage. The two are slightly different. 

 For example, a "1-year-old" by definition is 

 a seal in the period 1 January to 31 December 

 of its second calendar year, partly in its first 

 pelage and partly in its second. The quadratic 



■"■ Estimates by curve fitting, based on the weighted means (right-hand 

 col-umn) of table 10. 



^ For example, a "1-year-old" by definition is a seal in the period 1 

 January to 31 December of its second calendar year, partly in its first 

 pelage and partly in its second. 



Figure 7.--Molt mid dates; straight line fitted to data 

 from table 6; sexes combined. (Y» 267.53 + 3.59X.) 



models are based on calendar age of the seal 

 and should be interpreted accordingly. They 

 are mainly useful in showing that fiber popula- 

 tions increase at the same rate in males and 

 females through age 5, and that the popula- 

 tions level off earlier in females than in 

 males. The counts give a better understanding 

 of the fiber populations in youngest and oldest 

 animals than do the models. 



Variation in Number of Fur Fibers with Season 



The counts which are summed up in the 

 bottom rows of table 10 contain data from 



21 



