2 CORA SENNER WINKIN 



tible of rather exact registration. Moreover, artificial respiration may 

 be maintained throughout the reaction, and thus the activity of the 

 peripheral mechanisms, the heart, blood vessels and internal secretions, 

 be kept free from the central asphyxial changes. Furthermore, under 

 artificial respiration, the reaction may be obtained repeatedly in the 

 same animal. It has therefore offered an opportunity for analyzing 

 the factors involved in such an emergency reaction to inimical condi- 

 tions in the central mechanism. 



Since the work of Ludwig, Cyon and Bezold in the sixties, the im- 

 portance of the splanchnic vasomotor fibers for the production of 

 extensive changes in blood pressure has been recognized. The re- 

 lated action of the discharge of adrenalin into the blood stream has 

 recently received considerable emphasis. However, the degree to 

 which either the splanchnic constrictor fibers or the secretion of the 

 adrenal glands is involved under such conditions of stress as evoke the 

 anemic rise, has not been evaluated with sufficient accuracy. This 

 study has therefore been concerned particularly with the efferent 

 nervous pathways of the "anemic rise" of pressure: above all, with the 

 degree to which it involves the splanchnic constrictor fibers. The 

 extent to which splanchnic involvement has made for adrenal activity 

 has then been investigated. Finally, the influence of the cardiac 

 innervation, insofar as this may directly effect changes in the level of 

 blood pressure during anemia, has also been examined. 



Through the restriction of the effect of the arterial occlusion to the 

 head region alone, the activation of the vascular response by the medulla 

 oblongata is under close experimental control. Accordingly, the cen- 

 tral relations of the various nervous levels controlling the efferent 

 channels could also be investigated. Indeed, the analysis of the 

 peripheral factors was in large part undertaken in order to establish 

 more accurately the functional organization of the central nervous 

 mechanism upon which the vascular response depends, that is, the 

 extent to which the peripheral agents executing the vascular responses 

 of the intact animal are activated either by the higher nervous levels, 

 or by the spinal cord alone. 



This analysis was undertaken in connection with the studies on the 

 central nervous system carried out under Prof. F. H. Pike, which have 

 dealt particularly with the bearing of its organization on the problem 

 of "spinal shock." In connection with the problems here opened up 

 it was necessary to ascertain the exact nature of the peripheral and 

 central factors controlling the typical vascular response in animals in 



