266 /. J- Christian 



anophilia, whereas prolonged exposure to less severe fighting resulted in 

 normal sudanophilia with adrenal hypertrophy in the subordinate animals. 

 None of the dominant rats showed adrenocortical hypertrophy or changes 

 in sudanophilia in spite of the fact that they fought as much or more than 

 the subordinate animals. Barnett (1958) has recently published additional 

 evidence on a smaller number of rats from which he concluded that the 

 adrenal cortices of both subordinate and dominant animals hypertrophy. 

 Nevertheless his data show that the mean adrenal weight, relative or abso- 

 lute, of subordinate animals in a group of rats introduced into a colony was 

 appreciably greater than that of dominant animals. Barnett used very small 

 numbers of rats and based his conclusions on absolute rather than on rela- 

 tive adrenal weight, in spite of the fact that his animals varied from 250 to 

 400 gm. at the start and 170 to 420 gm. at the end of the experiment. He 

 concluded, on the basis of thirty rats, that there was no relationship between 

 adrenal weight and body weight for rats weighing more than 150 gm. This 

 conclusion may be ciuestioned for several reasons. In the first place the 

 mean adrenal weight of his animals increased with increasing body weight, 

 athough the differences were not significant. However, had larger numbers 

 of animals been used it is more than likely that a significant increase in 

 adrenal weight with increased body weight could have been shown. Other 

 data on over 1200 wild Norway rats shown conclusively that there is a 

 definite increase in adrenal weight with increasing body weights varying 

 from 50 through 600 gm., and that there was a significant linear relationship 

 between the logarithm of the adrenal weight and body length or weight 

 (Christian, 1954; Christian and Davis, 1955) . Finally, it is well known that 

 there is a definite tendency for the larger animals to be dominant, therefore 

 adrenal hypertrophy in smaller, subordinate rats would tend to make the 

 adrenals of dominant and subordinate animals weigh the same. It is of 

 considerable interest, however, that rats from colonies of mixed sex were 

 appreciably larger than those from all-male colonies. In general the amount 

 of sudanophilia in the zona fasciculata coincided with the weight data. 

 Nevertheless, Barnett's results appear to agree with those established earlier 

 as well as with the results of the experiments of other investigators. 



The above experiments warrant the general conclusion that in house mice 

 and Norway rats adrenal weight tends to be inversely related to social 

 rank in that dominant animals exhibit little or no increase in adrenal weight, 

 while subordinate animals show a marked increase. A word of caution should 

 be directed with regard to the interpretation of results with adrenal weights. 

 A hyperactive adrenal with a loss of cortical lipids may weigh less than a 

 less active gland containing a large amount of lipids. This has been shown 

 to be the case in mice (Christian, 1955a, 1959b) and evidently is also true 

 in Barnett's (1958) experiments in which the adrenals of his "interloper" 



