MODES OF DEATH, 110 



Venous "blood (say these observers), circulating through t'ne 

 arteries, has no directly poisonous operation, but is capable, 

 though much less effectually than arterial blood, of supporting 

 in some degree the irritability of the muscles ; and it appears 

 that the primary and main cause of the failure of the circulation 

 seems to be the difliculty with which the non-arterialized blood 

 passes through the capillaries of the lungs, and partly the imper- 

 fect stimulus afforded by the venous blood to the walls of the 

 heart, as well as its incapability to support the functions of the 

 brain and nervous system. The appearance of engorgement of 

 the pulmonary arteries and venous system generally, with dis- 

 tension of the right side and comparative emptiness of the left 

 side of the heart, seen after death, are more constantly visible in 

 the slower forms of apnoea than after sudden suffocation ; for 

 after sudden death blood seldom coagulates, and if the animal 

 is not shortly examined, the engorgement is apt to disappear 

 by gravitation. 



The conclusions of Sir James Kay Shuttleworth and of Mr. 

 Erichsen, although correct enough, fall rather short of a full 

 explanation ; for it has been ascertained by many observers that 

 when an animal is strangled by a tight ligature on the trachea, 

 and examined immediately after deatli, the lung tissue is always 

 found void of blood, whilst the jjulmonary artery, up to its 

 smallest branches, the great veins and the heart, are greatly 

 engorged. Dr. George Johnson, in explaining this, says that 

 some opposing power is brought 'into play, more than equal to 

 the propelling power of the heart, and that this opposition is due 

 to the firm contraction of the muscular walls of the ultimate 

 branches of the pulmonary artery. He calls this contraction 

 the stop-cock action of the ultimate pulmonary arteries. Dr. 

 Johnson proved by experiments of his own that this condition 

 exists whether the ligature be applied after or before a full 

 inspu-ation ; whether the lungs were at the time full or compara- 

 tively empty of air. " These," says Watson, " are the plain and 

 unquestionable facts of the case. They show that some oppos- 

 ing power must have been called into play more than equal to 

 the propelling power of the right ventricle of the heart. JS^ow, 

 such a power — and it is the only conceivable one — actually 

 exists at the very place where the venous current meets with its 

 curb, and it consists in the firm contraction of those muscular 



