252 /. J. Christian 



k. Eosinophil counts. The numbers of circvilating eosinophils are beyond 

 doubt diminished by adrenal factors and eosinophil counts are commonly 

 used to assess the response of the adrenal cortex to ACTH or indicate in- 

 creased pituitary-adrenocortical activity (Speirs and Meyer, 1949; Speirs, 

 1955). The reduction in eosinophils appears to result mainly from their 

 increased destruction under the influence of cortical hormones. A reduction 

 in eosinophils can be effected by epinephrine as well as by cortical hormones, 

 and there is evidence that the presence of cortical hormone is required for 

 epinephrine to produce an eosinopenia (Gordon, 1955). It is mainly with 

 respect to whether or not cortical hormones are necessary for the eosino- 

 penic action of epinephrine that the specificity of eosinopenia as an indica- 

 tor of increased adrenocortical activity has been questioned. Nevertheless, 

 if epinephrine produces a marked eosinopenia in the intact animal, eosino- 

 phil counts in mammals, especially wild, appear to have limited value. 

 Fear resulting from handling, trapping, etc., not only would produce 

 eosinopenia, but could produce it without necessarily having an increase 

 in adrenocortical activity. Nevertheless Louch (1958) used eosinophil 

 counts to assess adrenocortical function in relation to changes in popula- 

 tions of voles and with adequate precautions the use of eosinophil counts 

 for assessing adrenocortical activity in natural populations seems to have 

 considerable value in these experiments. However it is not possible to 

 state definitely whether the declines in eosinophils were due to cortical or 

 medullary hormones, although it seems logical that the former were respon- 

 sible and there was cortical hypertrophy. Southwick (1959) has also related 

 declines in eosinophil counts in mice to increased adrenocortical functions, 

 but again the role of epinephrine has not been evaluated. Eosinophils de- 

 cline about an hour after acute stimulation of the pituitary-adrenocortical 

 systems (Louch, 1958) ; therefore using counts as criteria of cortical func- 

 tion with respect to chronic stimuli has many inherent hazards. Acute re- 

 sponses to handling, fear, or line trapping could easily mask any effects pro- 

 duced by the chronic stimulus of changing population density. The relative 

 roles of epinephrine and of the cortical hormones in producing the observed 

 declines in eosinophils following emotional stimuli in mice must be assessed 

 before one can state with finality that the cause was increased cortical 

 activity. 



I. Neutrophil counts. A rise in circulating neutrophils accompanies in- 

 creased pituitary-adrenocortical activity, but similar changes can be in- 

 duced by so many factors that, even though they may involve increased 

 adrenocortical secretion, neutrophil counts are not very useful indices 

 with which to measure pituitary-adrenal activity. 



m. Liver glycogen. The accumulation of glycogen by the liver has been 

 used as a means of assaying various steroids for their activity on carbohy- 



