TEMPERATURE OF NEWLY-BORN CHILDREN. 439 



obliterated for some considerable time after birth ; respiration goes on as from 

 the beginning, and why should it after a few hours cease to exert the same 

 lowering influence which it exercised at first? It seems to me that the only 

 feasible explanation is to suppose that the hitherto unexercised influence of 

 the nervous system over the respiratory function is not at once called into 

 vigorous and efficient action — that though the influence required for inducing the 

 muscles of respiration to act is in full force from the beginning, there is still 

 awanting, or only partially supplied, that more delicate and less easily explained 

 agency without which, even though the blood may undergo the usual changes, 

 the due amount of heat is not generated; and that coincidently with the estab- 

 lishment of this influence does the temperature of the child rise to its normal 

 range. This explanation is quite in harmony with the fact that in delicate and 

 premature children the fall is greater than in vigorous ones and those born at the 

 full time, in whom also the normal standard is more rapidly reached, in conse- 

 quence probably of the more speedy establishment of the due nervous influence. 



(c). During the five days immediately succeeding that on which the tempera- 

 ture rose to a height which might be regarded as normal, we have seen that 

 the range was one degree below that of the adult, after due allowance had been 

 made for the difference resulting from the manner in which the thermometer was 

 applied. 



This lower range of the early period of extra-uterine life admits, I think, of 

 a very ready explanation. 



As a general rule, the degree of heat produced bears adefinite relation to the 

 activity of the respiration : in birds, in which respiration is very active, the 

 temperature is high; in reptiles, with a sluggish respiration, there is a low 

 temperature. 



Anything which interferes with the proper oxygenation of the venous blood, 

 or with the due supply of the purified fluid to the tissues, has a lowering effect on 

 the temperature. Such agencies are constantly at work in the newly-born child. 

 The patent condition of the foramen ovale and ductus arteriosus permit of so free 

 a commingling of the venous and arterial blood, that a lower temperature than 

 exists after the closure of these passages must result ; for, in the first place, less 

 blood goes to the lungs at each contraction of the right ventricle, and so less heat 

 is produced there ; and, in the second place, the blood which goes to the tissues 

 is less pure, and consequently less of an interchange takes place in the capillaries 

 of the systemic circulation. 



How long the child's temperature continues lower than that of the adult I am 

 not prepared to say, as my observations were limited to the first week of extra- 

 uterine life, but should think it probable that the adult standard of health is not 

 maintained till the foramen ovale and ductus arteriosus are closed, or nearly so. 

 This, however, is a mere hypothesis, and must remain so, as the time of closure of 



VOL. XXV. PART II. 5 TJ 



