side upward on a table, cut edge toward the 

 observer; light from two 15-watt "daylight" 

 fluorescent lamps coming toward the speci- 

 men at an angle of 45°, and toward the ob- 

 server (Munsell Color Company, 1954; Na- 

 tional Bureau of Standards, 1955). 



2. Maximum depth of underfur. — On a dry 

 mount, slant depth from epidermis to surface 

 of the underfur layer, all fibers in natural, 

 slightly bent, or wavy attitude. 



3. Percent guard hairs of previous gener- 

 ration . — A rough estimate of hairs more than 

 1 year old, from the evidence of worn tips and 

 faded blades; at magnification of SOX. 



4. Depth of skin, — Slant depth of the dried 

 dermis- plus-epidermis. 



hairs; percent mature and immature underfur 

 fibers . — Estimated on the basis of 100 guard 

 hair follicles and 20 underfur follicular 

 bundles on a paraffin mount, horizontal, near 

 the surface. 



STAGES OF MOLT 



Early in the present study the important 

 stages of molt were identified and defined. 

 Molt was analyzed primarily on the basis of 

 changes in the guard hair, since changes in the 

 underfur are difficult to follow. Once a new fur 

 fiber has erupted, it becomes invisible among 

 250 to 350 other fibers per mm. ^. The stages 

 of molt, and the duration of each, are: 



Resting Stage 



About 37 weeks; hair roots dormant. The 

 skin is white; the follicles are resting; the 

 hair roots are club-shaped, nearly colorless, 

 and without bulb. All fibers are mature. Near 

 the start of the resting stage in early winter 

 the outer guard hairs are dark and sharp- 

 tipped; near the end in late summer they are 

 faded and blunt or frayed. For an indefinite 

 period in the early resting stage the skin is 

 said to be "prime." 



Beginning Molt 



About 2 weeks; roots becoming active. All 

 evidence of molt is subsurface; at first not 

 visible to the naked eye. The first underfur 



bulbs are forming and are producing fiber 

 which are shooting toward the surface. Fe' 

 to many guard hair bulbs are forming. 



Early Molt 



About 6 weeks; new hairs erupting. Ne 

 guard hair tips are sprouting into the underfu 

 layer. Others are beneath the surface of th 

 skin, and still others have reached the oute 

 surface of the underfur pile. Black streakir 

 in the skin is more prominent than in ar 

 other stage. Up to 35 active guard hair bult 

 per linear cm. on a transverse section can h 

 seen. Up to 73 percent of the units at the sur 

 face contain twin guard hairs: old and nev 

 Colloquially, this is the "peepy" stage. 



5-6. Percent mature and immature guard j^^^.^ j^q^j 



About 4 weeks; new hairs maturing. The mai 

 wave of new guard hair tips has reached to c 

 beyond the outer surface of the underfur laye: 

 Last year's guard hairs, though worn, aresti 

 the longest hairs in the pelage. Pigment produc 

 tion at the base of the guard hair is declinin] 

 Old guard hairs are being shed rapidl; 

 Colloquially, this is the "rank" stage. 



Ending Molt 



About 3 weeks; roots regressing; a transitic 

 between late molt and resting. Molt is n( 

 visible to the naked eye. The longest hairs i 

 the pelage are those of the new crop, a few t 

 which are still growing. Many guard hair rooi 

 are finely speckled where the bulb has dis 

 appeared, but diffuse pigment remains. 



MOLT IN RELATION TO AGE, 

 SEX, AND SEASON 



For each of 671 specimens representir 

 animals older than pups, the stage of moltwa 

 diagnosed as resting, beginning, early, late, c 

 ending (table 2). 



Total Duration of the Molting Period 



Molting individuals were collected as earl 

 as 21 June and as late as 23 January of th 

 following year. In June, 5 of 64 seals take 

 were in beginning molt. The June-moltir 



