332 PULMONARY MUCOUS TISSUE. 



able variation is observed in the quantity of oxygen absorbed 

 and carbonic acid exhaled ; these exchanges have been shown 

 to be in direct proportion to the activity of the organs ; they 

 are greater in wakefulness than during sleep; alter eating, 

 more oxygen is absorbed, and more carbonic acid exhaled ; 

 movement, and muscular labor in general, increase these ex- 

 changes to their highest point ; intellectual labor, likewise, 

 increases them, as the nerve globules, and the nervous ele- 

 ments in general, consume oxygen like all other elements, 

 especially when they are at work. 



The nervous tissue may be said to require the largest 

 quantity of oxygen, that is, of arterial blood ; the first symp- 

 toms of asphyxia are agitation of the nerves, ringing in the 

 ears, dimness of sight, mental disturbance, and loss of con- 

 sciousness, all which begin in the cephalic part of the cerebro- 

 spinal system ; reflex actions of a medullary nature are also 

 produced (motions resembling those made in self-defence, in 

 flight, and in swimming; also excretion of the fecal matters, 

 the urine, the spermatic fluid, etc.), but these quickly dis- 

 appear. It seems that, at the moment when asphyxia takes 

 place, the carbonic acid accumulated in the blood acts upon 

 the nervous centres and excites them ; thus we find certain 

 physical acts, such as the memory, under these circumstances 

 carried to the highest degree ; this occurs in the case of 

 persons apparently drowned, who, on being restored to life, 

 state that at the moment of suffocation the memory reached 

 its highest -point : that they saw pass before their eyes in a 

 few seconds, and Avith astonishing clearness, the whole pre- 

 vious history of their life, many events which they supposed 

 had for ever been banished from thought and memory. 1 This 



1 Brown- Sdquard long since drew the attention of physiologists 

 to this exciting action of carbonic acid (see ' ' Journal de Physiolo- 

 gic," 1858, and following years). It is principally observed in the 

 muscles (both smooth and striated) which contract strongly in 

 animals killed by strangulation. The movements observed post 

 mortem, and the occasional and strange attitudes spontaneously 

 assumed by corpses (particularly of cholera patients) must be 

 ascribed to a similar cause. Cl. Bernard has recently demonstrated 

 that in the case of animals asphyxiated by carbonic acid (strangu- 

 lation), the temperature rises white the asphyxia lasts, and that this 

 increase of temperature occurs chiefly in the muscular system 

 (excited, no doubt, by CO 2 ), and are produced, as is always the 

 case, by chemical phenomena of combustion, increased by the con- 

 ditions of the asphyxia which are the cause of convulsions. In 

 this case the muscle entirely consumes the oxygen of the blood, 

 which thus furnishes material for exaggerated phenomena, and, 



