vitamin A potency of less than 50,000 "bpec" luiits per gram, and about 

 one- third of the livers yielded an oil having a potency in excess of 

 100,000 "spec" units per gram. (The liver of the average 3-year-old male 

 fur seal contrihutes ahout k percent of the weight of the "body and 5 

 percent of the wei^t of the skinned carcass.) 



Discussion 



The prime objective in 19^ was to find a means of identifying, 

 in the fresh bsdies, the livers of potential value. In this we have 

 partially succeeded. It ^jpears from the present and our earlier woik 

 that paleness of liver is fairly indicative of high vitamin A potency. 

 Thus, for the saii5)le of 51 pale livers taken in 19^ and reported here, 

 the mean vitamin A potency of the liver oil was 137,000 "spec" units per 

 gram of oil. For the random sample of 95 livers taken in 19^7, the mean 

 potency was 57,^00 "spec" units. 



Althou^ the animals sampled were of the same age and sex, they 

 were killed a year apart. It is barely possible that the observed dif- 

 ference in vitamin A potency was dae to a difference in tiie 19^7 diet and 

 the 191+8 diet of the study animals. Considering, however, the wide extent 

 of the feeding range of the fur seal herd, the probability is great that 

 the diet from one year to the next is fairly \mifom. Hence the difference 

 in vitamin A potency probably stems from some source other than annual 

 variation in food. 



Granted that paleness of the liver and high vitamin A potenisy are 

 directly correlated, the next move is to find out what factors contribute 

 to paleness. The li^t color is uniform throughout the liver and is not 

 limited to the surface. It may, to a sli^t extent, be caused by an increase 

 in fat content. Thus, in the 19^8 sanple of pale livers, the oil concen- 

 tration was 3.91 percent, vftiile in the 19^7 random sanple of livers it was 

 2.99 percent. 



The livers having a hi^ vitamin A potency seem to contain more 

 oil. If tile 51 livers are divided into two groups, the first (with 35 

 livers) having a potency of less than 100,000 "spec" units and the second 

 (with 16 livers) having a potency of more than 100,000 "spec" units per gram 

 of oil, it is found tiiat the mean concentration of oil in the liver of the 

 first groi?) is 3.63 percent and in the second, h,55 percent. A similar 

 relationship has been observed by Braekkan (19^) in whale liver oil. In 

 fin, blue, and sperm whales he states that "tiie potency is usually hi^est 

 in the sanples having the highest content of fat." 



Of all the livers available on the killing field, the palest one- 

 tenth mi^t be used commercially. These are worth, at 16 cents a million 

 units of vitamin A, about $0.88 each, f.o.b. Seattle. Furthermore, among 

 the palest one- tenth there is a still smaller fraction, representing about 

 three percent of all tiie livers, which are worth about $2.72 each. Farther 

 observations of carcasses on the killing fields are planned in an attempt 

 to segregate the livers of hi^ vitamin A potency. 



3 



