EFFECTS OF SUSPENSION OF RESPIRATION. 591 



removed into the air before the insensibility is considerable, they then quickly 

 recover. When the body is examined, the heart is seen beating strongly 

 while the diaphragm is motionless ; the \vhole blood in the veins, as well as 

 in the arteries, is of a bright scarlet colour; and several of the membranous 

 surfaces have the same tint. The blood is observed to coagulate with re- 

 markable rapidity ; and it is to the alteration in its properties, occasioned by 

 the hyper-arterialization, and indicated by this condition, that we are proba- 

 bly to attribute the fatal result. There can be no doubt that in this instance 

 an undue amount of oxygen is absorbed ; and it does not seem unlikely that 

 one cause of the fatal result, is a stagnation of the blood in the systemic capil- 

 laries, consequent upon the want of sufficient change in its condition. When 

 Nitrogen or Hydrogen is breathed, for any length of time, death results from 

 the deprivation of Oxygen, rather than from any deleterious influence which 

 these gases themselves exert. Death is also caused by the inhalation of 

 several gases of an irritant character, such as Sulphurous, Nitrous, and Muria- 

 tic acids : but it is doubtful how far they are absorbed ; or how far their 

 injurious effects are due to the abnormal action, which they excite in the 

 lining membrane of the air-cells and tubes. It cannot be doubted, that mias- 

 mata and other morbific agents diffused through the atmosphere, are more 

 readily introduced into the system through the pulmonary surface than by 

 any other ; and our aim should therefore be directed to the discovery of some 

 counteracting agents, Avhich can be introduced in the same manner. The 

 pulmonary surface affords a channel for the introduction of certain medicines 

 that can be raised in vapour, when it is desired to affect the system with them 

 speedily and powerfully ; such are iodine, mercury, tobacco, stramonium, &c. 



4. Effects of Suspension of Respiration. 



778. We have now to consider the results of the cessation of the Respira- 

 tory function, and the consequent retention of carbonic acid in the blood. If 

 this be sufficiently prolonged, a condition ensues, to which the name of 

 Asphyxia has been given ; the essential character of which is the cessation 

 of muscular movement, and shortly afterwards of the circulation ; with an 

 accumulation of blood in the venous system. The time which is necessary 

 for life to be destroyed by asphyxia varies much, not only in different animals, 

 but in different states of the same. Thus Warm-blooded animals are much 

 sooner asphyxiated than Reptiles or Invertebrata ; on the other hand, a hyber- 

 nating Mammal supports life for many months, with a respiration sufficiently 

 low to produce speedy asphyxia if it were in a state of activity. And among 

 Mammalia and Birds, there are many species which are adapted, by peculiari- 

 ties of conformation, to sustain a deprivation of air for much more than the 

 average period.* Excluding these, it may be stated as a general fact, that, if 

 a warm-blooded animal in a state of activity be deprived of respiratory power, 

 its muscular movements (with the exception of the contraction of the heart) 

 will cease within five minutes, often within three ; and that the circulation 

 generally fails within ten minutes. Many persons, however, are capable of 

 sustaining a deprivation of air for three, four, or even five minutes, without 

 insensibility or any other injury ; but this power, which seems possessed to 



Thus, the Cetacea contain far more blood in their vessels, than do any other Mamma- 

 lia ; and these vessels are so arranged that both arteries and veins are in connection with 

 large reservoirs or diverticula. The reservoirs belonging to the former are usually full ; but 

 when the Whale remains long under water, the blood which they contain is gradually in- 

 troduced into the circulation, and, after becoming venous, accumulates in the reservoirs con- 

 nected with the venous system. By means of this provision, the Whale can remain under 

 water for more than an hour. 



