COEONARY PERFUSION OF EXCISED HEART 15 



amount, cut off the CHCI3 supply and resupply the normal Ringer-Locke 

 solution. Observe the further diminution and the gradual recovery of the 

 heart's beat. Note that the rate of beat is not altered if the temperature of 

 the perfusion fluid containing the CHCI3 be maintained. 



ANNOTATION 



Obs. 8. The effect of adrenal extract upon Obs. 9. See Sherrington and Sowton, 



the perfused heart was discovered by Oliver Committee of the Brit. Med. Assoc. 1903 



and Schafer and is mentioned in their ori- (Brit Med. Jnl. 1903, and Thompson Yates' 



ginal paper (see Annotation to exerc. I). Beports, vol. v, p. 69, Liverpool, 1903). 



The effect resembles that produced by A solution ten times weaker than the 01 per 



stimulating the sjonpathetic cardiac nerves, cent, which you use in the experiment will 



Adrenal extract greatly increases oxygen cause distinct depression of the beat. The 



consumption by the heart (Barcroft and effect produced by a given percentage of 



Dixon, Jnl. of Physiol, vol. xxxv, p. 182, CHCI3 in Ringer-Locke is greater than in 



1910), and roughly proportionately to the blood and than in blood diluted with saline 



increase in beat-rate (Lovatt Evans and solution (Sherrington and Sowton, Brit. 



Sagoro Ogawa, ibid. vol. xlvii, p. 446, Med. Jnl. 1904), the solution tension being 



1914). higher in the Ringer-Locke. 



EXERCISE lY 



INSPECTION OF THE LUNGS AND BEATING HEART IN SITU; INFLUENCE 

 OF INTRA-PERICARDIAL PRESSURE AND OF FARADIZATION OF THE 

 VAGUS NERVE. THE CAPILLARY CIRCULATION VIEWED BY THE 

 MICROSCOPE 



I. Attached to the tubing from the ventilating pump a decapitate carcase 

 is provided. The inflations supplied by the pump to the lungs are at the rate 

 of about 30 a minute. The amount of distension of the lungs by each inflation 

 can be increased or lessened by constricting or leaving freer the short rubber 

 tube on the side arm of the tracheal cannula, adjusting the little spring clip 

 on it. Examine the preparation for indications of a satisfactory condition of 

 circulation, respiration, and nervous system. The heart-beat should be easily 

 perceptible by palpation through the chest-wall ; should be regular and of a rate 

 of about 100 per minute. If the ventilation of the lungs is too slight or too 

 forcible, readjust by regulation by the spring clip. Eeadjustment of the lung 

 ventilation will often improve an enfeebled heart's action. The knee-jerk 

 should be brisk ; to elicit it lift the limb slightly by the thigh with hip semi- 

 flexed and tap the patellar tendon. 



II. Set your Einger-Locke fluid containing cotton-wool swabs to warm 

 to 37° C. See that you have ready, in addition to the usual operating 



