372 



Dr. S. W. Patterson. The Antagonistic 



manometer a small piston recorder was attached for graphic records ; O'l grm. 

 of hirudin was added to the blood to prevent clotting. 



In the case of cats, the systemic schema (consisting of the arterial resist- 

 ance and venous reservoir) used was that described by Knowlton and Starling ; 

 while the other experiments were made at various times with the different 

 modifications of method which have marked the evolution of the systemic 

 schema, and which have been reported in the communications from the 

 University College laboratory during the last two years. Eeferences to these 

 will be made iu the discussion of results, as the separate points brought out 

 are considered. 



In all cases the systemic output was measured directly into a graduated 

 vessel by means of a stop-watch, and is recorded in cubic centimetres per 

 10 seconds, the output per minute being this observed figure multiplied by 6. 



When the heart volume was recorded, a glass plethysmograph on the 

 ventricles was used similar to that described by Henderson (13), and the 

 cardiometer was connected by air conduction with various recorders. 



In some experiments the mean pressures in the left auricle were recorded 

 from a water manometer connected with a small cannula tied in the appendage 

 of the left auricle. 



The adrenalin (Parke, Davis and Co.) was mixed with the blood in the 

 venous reservoir, while the carbon dioxide was administered from a gas bag. 

 The figures given of the percentages of C0 2 in the gas bag can only approxi- 

 mately show the percentage in the air at the trachea, as various types of 

 artificial respiration apparatus were used, and were connected to the trachea 

 by sometimes considerable lengths of piping, and as the side slot of the 

 tracheal cannula was more or less open. 



Results. 



In the heart-lung preparation, as in the intact animal, there are three 

 circles of blood from one side of the heart to the other, one from the right 

 ventricle to the left auricle through the lungs and two from the left ventricle 

 to the right side of the heart, one of which passes through the schema and 

 represents the systemic circulation in the whole animal, and the other passes 

 through the coronary circulation. The total output of the left ventricle 

 consists, therefore, of the systemic output, which was measured directly in 

 our work, together with the output through the coronary vessels; so the 

 question of the relation of the coronary output to the systemic output under 

 normal conditions and under the influence of carbon dioxide and adrenalin 

 must first be considered. 



Relation of Coronary Sinus Flow (as Index of Total Coronary Output) to 



