438 DR T. J. MACLAGAN ON THE 



hour 2 0, 4, and during the second half hour (after respiration was established) 

 5°7. In all other cases in which a comparison could be made the fall was much 

 greater during the first half hour than during the second ; in this one the reverse 

 was the case ; and the only explanation of this circumstance is to be found in 

 the tardy establishment of the respiratory act. So far as one case can do so, 

 this one shows that it is not until the child breathes that the temperature falls 

 to any great extent; though the diminished range may also be partly explained by 

 the cooling influence of the external air on the blood in the very active cutaneous 

 circulation. 



But the question naturally arises, Why should the respiratory act, which in 

 the adult has a heat-producing effect, have an opposite result in the infant ? The 

 answer involves a brief consideration of the whole question of the production of 

 animal heat. To the various theories which have at different times been advanced 

 to account for this I shall not allude further than to say, that all have given 

 place to that which ascribes it to chemical action — to the changes which are con- 

 stantly going on in the blood in all parts of the capillary system — general and 

 pulmonic. As these changes take place in organs and parts which are dependent 

 for the proper performance of their functions on the integrity of the nervous 

 system, it follows that the amount of heat produced is apt to be modified by the 

 operation of that system. Medicine abounds in illustrative cases in which a part 

 of the body, a limb for instance, in consequence of being deprived of its nervous 

 supply by disease or accident, has a lower temperature than it had when that 

 supply remained intact. 



Sir B. C. Brodie (I quote from Kirkes' " Physiology") " found that if 

 artificial respiration was kept up in animals killed by decapitation, division of 

 the medulla oblongata, destruction of the brain, or poisoning with worara poison, 

 the action of the heart continued, and the blood underwent the usual changes in 

 the lungs, as shown by the analysis of the air respired, but that the heat of the 

 body was not maintained ; on the contrary, being cooled by the air forced into 

 the lungs, it became cold more rapidly than the body of an animal in which 

 artificial respiration was not kept up." 



Absence of the due nervous influence is, I believe, the true explanation of the 

 rapid and transient lowering of the child's temperature during the first few hours 

 of extra-uterine life. It is, indeed, unlikely that the child should have its con- 

 nection with the mother severed, and commence its new and independent 

 existence with patent foramen ovale, unclosed ductus arteriosus, and lungs 

 hitherto untried, and from the first maintain the temperature imparted to it by 

 the parent ; but, as already explained, the existence of this peculiar state of the 

 organs of circulation is inadequate to account for a fall so very rapid and of so. 

 short duration. Closure of the foramen ovale and ductus arteriosus cannot 

 explain the speedy return to the normal range, for these passages are not 



