

8 days after 30-second exposure 



13 days after 30-second exposure 



22 days after 20- second exposure 



41 days after 20- second exposure 



Figure 27. — Changes in cryogenic brands of the naturally oare flipper skin of fur seal pups, Zapadni Reef 



Rookery, St. Paul Island, 13 July to 23 August 1966. 



Some 15- second brands were satisfactory, 

 but white hair growth was not dense. Many of 

 the 25- and 30-second brands were contracted, 

 and some 30-second brands destroyed the 

 hair follicles. 



Standardization of the technique to that 

 which produced satisfactory marks in these 



trials should result in an excellent method 

 for pernrianently marking fur seals. Branded 

 seals must be observed for several years, 

 however, to be certain that depigmentation 

 of the treated follicles is permanent. Errors 

 in chilling the marking instrument, timing 

 the exposure, and achieving uniform contact 



48 



