286 BENSON" A. COHOE 



of the disease, must necessarily resolve itself into the broader viewpoint 

 of the functions of the chromaphil system (medulla) and of the interrenal 

 system (cortical tissue). Among the better known hypotheses concerning 

 the function of the medulla are the following: (1) The tonus theory, 

 which postulates that the internal secretion of the medulla (epinephrin) 

 serves to maintain the normal blood pressure and to establish a state of 

 tonus in smooth muscle fibers, innervated by the sympathetic nervous 

 system in general. Considerable evidence has accumulated, however, to 

 render this theory no longer tenable. The researches of Moore and Purin- 

 ton(&) and others have shown that very small doses of epinephrin have a 

 hypotensive action, and the more recent investigations seem to indicate that 

 the circulating blood contains little or no epinephrin. Trendelenburg(a) 

 found the epinephrin content of the blood from the carotid artery of the rab- 

 bit to be not more than one part in one or two billions, a quantity quite in- 

 active in maintaining blood pressure. Moreover, the investigations of Hos- 

 kins(o-), Gley(/) and others have offered evidence for the belief that epi- 

 nephrin is not present in the blood in quantities sufficient to exert any ap- 

 preciable effect on the sympathetic nervous system. The existence of a true 

 epinephrinemia is doubted by many physiologists. The researches of 

 Cannon (a) and his associates led them to believe, however, that during 

 times of stress (e. g., the emotions of fear, pain, rage, etc.) the suprarenal 

 is stimulated to secrete epinephrin in sufficient amounts to produce an 

 action on the sympathetic system. This observation gave origin to (2) the 

 emergency theory, according to which the function of the suprarenal me- 

 dulla is the discharge of epinephrin in times of emergency only. There is 

 considerable evidence of an experimental nature to substantiate this 

 theory, although some investigators ( Stewart (c), Gley) have failed to con- 

 firm various of Cannon's observations, A further possibility which has 

 been suggested concerning the function of the medulla is that minute quan- 

 tities of epinephrin are necessary for the metabolism of the tissues 

 (Elliott(e)) (3) the metabolic theory. Sajous(a), since 1903, has 

 maintained the view that epinephrin plays an important role in the re- 

 spiratory mechanism, as a constituent of the hemoglobin, and has brought 

 forward considerable evidence in support of this theory. The general con- 

 clusion which may be drawn from the results of an extensive experimental 

 research concerning the function of the medulla, is that no satisfactory 

 evidence has been adduced to show that the secretion of the chromaphil 

 tissue (medulla) is of any service whatever in the normal state of the 

 organism (Hoskins). The investigations of Stewart (e) appear to demon- 

 strate that the secretion of epinephrin is not indispensable for life. This 

 author, however, concludes that the effects, which epinephrin produces, are 

 not gross effects, which are easily discernible, and that it is not possible in 

 the present state of our knowledge to assign to any of these effects a role 

 of definite physiological significance. The results of physiological re- 



