158 



Scientific Proceedings (39). 



substances for as long as six days, surviving ox arteries were chosen 

 as the best material for the study of this other factor in the arterial 

 wall, namely, tonus. These vessels were examined first cold and 

 contractured, then warmed to body temperature, then stretched 

 to relaxation by 100 millimeters internal pressure, then after the 

 introduction of adrenalin, and finally of barium chloride, into the 

 internal circulation. In each case a control tracing of the re- 

 action of a strip of the vessel according to Meyer's method, carried 

 under identical conditions and tested at the completion of each 

 stage of the experiment, was made. The surviving character of 

 the vessel was thus demonstrated. 



Of 38 common carotids and 4 mesenteries from the ox, the 

 following gave results free from obvious error: 



Seven ox carotids. 

 15° C. 37° C. Stretched. Adrenalin. Barium chloride 



Maximum 68.5 22 9.5 10.5 28.5 



Average 42.8 14.3 6.6 8.9 15.5 



Minimum 25 8 4.5 7.5 9 



Four ox mesenteries. 



Maximum 52 9 5 8 55 



Average 25.1 6.5 3.8 6.6 29.5 



Minimum 10.5 42 6 18 



These observations demonstrate very clearly the relation be- 

 tween tonus of the arterial wall and its resistance to compression. 

 A definite opinion as to the possible maximum effect of tonus, and, 

 therefore, the placing of a numerical value for this factor of error, 

 is not possible as yet. 



101 (511) 



A simple device for regulating the administration of ether or 

 chloroform, with either artificial or voluntary respiration. 



By A. 0. SHAKLEE. 



[From the Department of Physiology and Pharmacology of the 

 Laboratories of the Rockefeller Institute for Medical Research.] 

 In the course of a study by Dr. Meltzer and myself of the use 

 of continuous insufflation in the treatment of various forms of 

 fatal poisoning, the apparatus described below was devised to 

 simplify the control of anesthetic and pressure of air entering the 



