CARDIOVASCULAR CHANGES DURING CEREBRAL ANEMIA 3 



which either no lesions within the central system were undertaken, or 

 when these were inflicted, no interval for recovery after the operation 

 was allowed. In comparison with such data, a study of the vascular 

 responses after recovery from transection of the spinal cord could be 

 undertaken more intelligently, and the actual changes wrought by the 

 so-called shock effect evaluated with greater precision. 



HISTORY OF THE METHOD. Initiated by the very early work on 

 abdominal ligation of Stenson (1) and Swammerdam (2), Magendie 

 and Poiseuille (3) and Sir Astley Cooper (4) in the early nineteenth 

 century worked out the procedure of cerebral ligation, particularly 

 the isolation of the four chief arterial channels to the head, and noted 

 the circulatory changes which followed. Batelli (5) and Hill (6) have 

 given the earlier history of the procedure in some detail. 



The experiments of the eighteen fifties and sixties led to the recogni- 

 tion of the nervous organs as the chief agents in activating the changes 

 following arterial ligation: thus the work of Kussmaul and Tenner 

 (7), Brown Sequard (8), (9) and Vulpian (10) on the head area and of 

 Schiffer (11) on the spinal cord. The emphasis of the importance of 

 the medulla for the maintenance of life as given by the work of Le 

 Gallois and its extension by Flourens (12) was still more increased by 

 the localization in the same region of the vasoconstrictor center as soon 

 accomplished by Ludwig (13), Owsjannikow and Dittmar, and soon, 

 led up to the most complete studies on occlusion of the head arteries 

 carried out by Sigmund Mayer (14), (15). Mayer not only described 

 the series of changes following anemia with great detail and accuracy, 

 but also recognized that the elicitation of the anemic rise was dependent 

 on conditions of functional conductivity within the brain stem. He 

 also saw that occlusion of the head arteries was comparable to decapi- 

 tation with the knife, and that the various functions retained following 

 cerebral ligation were all to be attributed to the activity of the spinal 

 cord, notably the residual spinal level of blood pressure of 50 to 60 mm. 



Gouty (16) produced circulatory obstruction in the head region by the 

 injection of lycopodium spores. This work, contemporaneous with 

 that of Mayer and equally detailed, but carried out under the influence 

 of the earlier work of Goltz (17), (18) and Vulpian, stressed the residual 

 spinal functions, maintained following isolation of the medulla. Sub- 

 sequent work on cerebral anemia was almost exclusively done from 

 this point of view. Thus the papers of Schlesinger (20), Kowalewsky 

 and Adamtik (21), Bochefontaine and Vulpian (22), Mayer (23), 

 attempted to combat this viewpoint by an analysis of the differential 



