PHYSIOLOGY. 



ducted on the principles just mentioned. 

 Where noxious vapours, as those of pri- 

 vies, or burial places, or certain gases, as 

 sulphurated and phosphorated hydrogen, 

 produce it, there seems to be an action 

 of some poisonous or deleterious substan- 

 ces on the nervous system through the 

 medium of the lungs Intoxication is 

 quite different from asphyxia; it induces 

 a profound sleep, or insensibility, in which 

 the pulse still beats, and respiration goes 

 on, altnough slowly. 



The lungs are organs of secretion, and 

 separate from the venous blood, circulat- 

 ing through them in the pulmonary arte- 

 ry, ;md loaded wiih serum, a very abun- 

 dant watery vapour, called the breath, 

 and shewing itself in separate globules 

 when condensed by a cold and smooth 

 surface, as that ot glass or metals. As 

 the cessation of respiration is one of the 

 most obvious and easily recognisable 

 symptoms of death, the intimate connec- 

 tion between it and life has been noticed 

 even by the vulgar, and hence life itself, 

 and even the soul, have been supposed to 

 reside in the breath. Thus a'nima, in La- 

 tin, denotes the breath, the life, or the 

 soul. The breath of life is a familiar 

 phrase in our own language, and the 

 " animam efflavit" of the poet, which li- 

 terally means blew out his breath," is 

 employed to signify " died." We cannot 

 admit that this watery vapour is formed 

 by the oxygen of the atmosphere uniting 

 with the hydrogen of the venous blood, as 

 ihis combination, performed out of the 

 body, is attended with phenomena of de- 

 flagration that do not occur in the pre- 

 sent instance. The quantity of this se- 

 cretion is said to equal that of the skin ; 

 it should be distinguished from the mu- 

 cus secreted on the interior surface of the 

 bronchiae and trachea, which is thrown off 

 by strong expirations, and forms the mat- 

 ter of expectoration. 



Mmal heat. The power which living 

 bodies possess of maintaining the same 

 degree of heat under every change of sur- 

 rounding temperature, is one of their 

 most surprising phenomena, and one 

 which occupies a very prominent station 

 in that complicated assemblage of circum- 

 stances denoted by the term life. The 

 temperature of the blood, and of the in- 

 ternal parts of the body in general, is 

 stated at about 98 Fahrenheit. In Mr. 

 Hunter's experiment, he found the heat 

 under the tongue, and at the bulb of the 

 urethra, to be 97 ; in the rectum 98^ ; in 

 the rectum of an ox and rabbit 99| ; of a 

 Iren 103 ; in the heart, liver, and stomach 



of animals 100 and 10i. These tempe- 

 ratures, instead of varying like those of 

 inanimate bodies, according to the sur- 

 rounding media, and consequently tend- 

 ing to a state of equilibrium, are maintain- 

 ed with very little deviation under very 

 great varieties of atmospheric heat. Pal- 

 las sustained a cold of 80 below in Si- 

 beria, and Gmelin of 126 in the same 

 country. On the contrary, temperatures 

 of 120 and more above have been ob- 

 served in Africa and America. Linings 

 saw the thermometer at 126 in Carolina ; 

 but when placed under the tongue, or in. 

 the axilla, it sunk to the point of animal 

 heat. Much higher degrees of artificial 

 temperature have been supported by the 

 human body. Girls in France staid in au 

 oven where fruit and meal were baking; 

 for ten minutes, without inconvenience, 

 the thermometer at 265. Dr. Fordyca 

 and Sir Joseph Banks supported nearly an 

 equal degree of artificial hoat in this 

 country. 



From these facts, it is obvious that, al.' 

 though in rare instances* the surrounding 

 heat is greater than that of our own bo- 

 dies, it is generally considerably less; 

 Hence we roust explain the powers by 

 which our temperature is maintained so 

 much above tlKit of the medium in which, 

 we live. This explanation is now gene- 

 rally founded on the chemical changes 

 which the blood undergoes in the lungs, 

 and in its circulation through the body, 

 which subject is considered under the ar- 

 ticle HEAT. There are many circum- 

 stances in favour of this explanation ; as 

 the increased heat produced by the acce- 

 leration of the circulation by exercise, &c> 

 the coldness of a limb, when the nutrient 

 artery is tied ; the various degrees of tem- 

 perature in different animals correspond- 

 ing with the perfection of their pulmonary 

 system, &c. There are also several facts 

 which show, that the living powers of the 

 constitution, or part, greatly influence the 

 evolution of heat, independently of the 

 consumption of oxygen in respiration. The 

 coldness of palsied limbs, the increased 

 heat of parts in inflammation, and of the 

 whole skin in febrile complaints, are suffi- 

 cient to prove this. But it is most clear- 

 ly demonstrated by an experiment of Dr. 

 Currie's. He placed a man in a cold bath 

 of 40, which at first diminished his tem- 

 perature, but it soon regained the natural 

 standard. Here there must have been a 

 great evolution of heat to keep up the 

 temperature under circumstances so 

 strongly tending to depress it; yet the 

 consumption of oxygen was less than 



