120 PATHOLOGY. 



fibres of the minute arteries, tlie function cf which is to reguLate 

 the blood supply in accordance with the varying requirements 

 of the part. This function again is determined by those un- 

 sleeping sentinels the (vasa-motor) nerves. Were it allowable, 

 for the sake of illustration, to impersonate the vital forces con- 

 cerned in this marvellous adaptation, we might liken the process 

 to the intelligent stopping of the traffic on an obstructed line of 

 railway by a backward telegram." 



In order to test the correctness of Dr. George Johnson's 

 experiments, I have repeatedly examined strangled dogs, and 

 found that the heart will continue to beat for more than three 

 minutes after the respiratory efforts have ceased, and that the 

 lungs and great vessels are always as he has described them, 

 namely, the lung substances pale and empty, the pulmonary 

 artery and right side of the heart, with the cavas, immensely 

 engorged, and the pulmonary veins and left side of .the heart 

 containing a small quantity of venous blood. From these experi- 

 ments it appears very conclusive that death by apnoea occurs in 

 two ways, and that two distinct pathological conditions of the 

 lungs are observable after death : — 1st. When death is sudden, 

 as from suffocation by strangulation, drowning, or any cause 

 whereby the supply of air is suddenly cut off, the stop-cock 

 action of the ultimate pulmonary arteries prevents the blood 

 from flowing in its ordinary quantity to the pulmonary capil- 

 laries, veins, and left side of heart, and that the lungs are pale 

 when examined immediately after death : 2d. Wlien death more 

 slowly occurs, the blood accumulates in all the vessels of the 

 lungs, which after death appear engorged, congested, and black. 

 This is the condition of the lungs seen when an animal is 

 galloped to death, in pulmonary apoplexy, and congestion ; and 

 in death from some acute diseases, where towards the close of 

 the disease the heart becomes too enfeebled to propel the blood 

 tlu'ough the intricacies of the pulmonary system, or when the 

 blood itself becomes so altered as to be incapable of projDcr 

 arterialization. 



To prevent death by apncea, it is obvious that the respiratory 

 function must be restored where it is defective, that all impedi- 

 ments to the passage of pure air into the lungs must be removed. 

 The subject of treatment will, however, be considered in another 

 place, and I may merely state here that nothing has been found 



