226 



Dr. W. H. Gaskell. 



[Mar. 11, 



consequence of the operation of being tied on the cannula, are less in 

 height and more pointed in appearance, i.e., remain a shorter time at 

 the height of contraction than those which are obtained after the blood 

 has been passing some time. 



2. The tonic condition is in all probability partly due to the alkali- 

 nity of the blood. 



a. After the ventricle or apex beating with artificial blood solution 

 has been brought to standstill by replacing the blood with " normal " 

 salt solution, then an alkaline salt solution (1 sodium hydrate to 20,000 

 normal salt solution) causes beats to reappear, and again the ventricle 

 stops beating, but no longer in the position of diastole, the standstill 

 that now occurs is always a systolic not a diastolic standstill. 



b. When the ventricle or apex is beating under the influence of an 

 artificial blood solution and the alkaline solution be sent through, then 

 the resulting curve shows how the alkaline standstill is brought about, 

 every contraction is as powerful as with the blood solution, the cavity 

 being closed each time, but every relaxation is less perfect, and of 

 shorter duration than the previous relaxation, while the period of full 

 contraction in each beat is progressively lengthened, the rate of rhythm 

 not being much altered ; at last each relaxation becomes invisible, and 

 the lever traces a straight line at the level of the height of full con- 

 traction. 



c. When the apex is not beating, but is motionless in the position 

 of complete relaxation, as is frequently the case when salt solution 

 alone is sent through, then the alkaline solution brings it very 

 gradually from the position of extreme relaxation to that of extreme 

 contraction without the necessary production of a single beat. 



Further, if during this tonic action of the alkaline solution, artificial 

 beats be produced, then, as in the case just mentioned, the time of 

 full contraction in each beat is lengthened as the tonicity rises. 



3. Dilute acid solutions, such as lactic acid (1 lactic acid to 20,000 

 normal saline solution), lower the tonicity of the cardiac muscle. 



a. When the lactic acid solution is sent through a beating ventricle 

 or apex, then a curve is produced nearly the exact converse of the 

 curve obtained from alkaline solutions ; the separate beats progressively 

 diminish in force, present a pointed appearance, owing to the extreme 

 shortness of the time of full contraction, and very quickly the 

 ventricle or apex remains still in the position of extreme relaxation. 



b. When by means of the acid solution the beats have been much 

 lowered in force, then the alkaline solution can bring them back to 

 their original force and character, and then produce its own 

 characteristic effect, and if the acid solution be again sent through, it 

 gradually overpowers the action of the alkali, and the apex or 

 ventricle slowly falls from a condition of extreme contraction to one 

 of extreme relaxation. 



