1880.] On the Tonicity of the Heart and Arteries. 221 



c. If the acid solution has brought about a condition of nearly 

 absolute relaxed or atonic standstill, then removal of the acid by salt 

 solution does not improve the beats, and does not raise the tonicity, 

 but immediately the alkaline solution is sent through, the tonicity 

 begins to rise, and the beats are strengthened until the ventricle 

 passes into the condition of systolic or tonic standstill. 



d. The reverse case is also true ; although salt solution sent through 

 after the alkaline solution will very gradually bring the ventricle from 

 the contracted to the dilated condition, yet the lactic acid solution 

 produces the same effect with much greater rapidity. 



e. These very dilute alkali and acid solutions do not produce their 

 effects by permanently injuring the cardiac muscle, for in either case 

 it is possible to restore the beats to their original strength and character 

 by sending the artificial blood solution through. 



4. Certain alkaloids act in this respect in the same manner as 

 alkalies, others as acids. 



a. Digitalin or antiarin in artificial blood solution or in normal salt 

 solution produce exactly the same effect upon both the beating ventricle 

 and the non- beating apex as the alkaline salt solution. 



b. Blood solutions containing muscarin and pilocarpin gradually 

 diminish the force of the beat without necessarily slowing the rate of 

 rhythm until the ventricle stops beating in a condition of relaxation, as 

 in the case of lactic acid solutions ; at the same time the beats show all 

 the characters of the atonic beat. 



c. Atropin acts in the same direction as alkalies, but only raises the 

 tonicity to a slight extent, at least with the dilute solutions hitherto 

 employed. 



5. The tonicity of the muscles of the smaller arteries is increased by 

 alkalies and lowered by acid solutions. This is concluded from the 

 action of the alkaline and lactic acid solutions upon the vessels of the 

 mylohyoid muscle, upon the rate of flow from the abdominal vein when 

 the solutions are sent through the legs alone and upon the mesenteric 

 vessels. 



In all cases with the alkali solution the arteries contract, the rate of 

 flow diminishes or ceases altogether, and as long as the alkali solution 

 is passing through the contraction remains ; with the lactic acid solu- 

 tion, on the other hand, the arteries dilate to their full extent, the rate 

 of flow is markedly increased, and no constriction takes place unless 

 the alkaline solution be again sent through. 



The author reserves for another occasion a fuller description of his 

 results, as well as a discussion of their bearings. 



