510 NUTRITION. 



ductors over any of the superficial vessels, like the radial. Of course it is impossible to 

 note the actual temperature in the two sides of the heart in the human subject during 

 life ; but Prof. Lombard endeavored to arrive at the same end, by calculating that, if all 

 the sources of refrigeration in the lungs were artificially removed, the blood in the arte- 

 ries should gain about the same amount of heat that would be lost under ordinary condi- 

 tions. To effect this object, he breathed air saturated with moisture and of the same 

 temperature as the circulating blood. "If, then, when respiration takes place under 

 ordinary circumstances, the blood is cooled one-third of a degree (cent.) in passing through 

 the luDgs, the temperature should be raised so much ; that is to say, one-third of a degree, 

 when we respire air at the temperature of the blood and saturated with the vapor of 

 water, all loss of heat then being impossible." In numerous experiments performed upon 

 this principle, Prof. Lombard failed to observe a sufficiently marked elevation of tempera- 

 ture to justify the conclusion that the blood is ordinarily cooled in passing through the 

 lungs. These experiments cannot be so positive as those made by introducing thermome- 

 ters into the heart in living animals without opening the chest or disturbing the circula- 

 tion ; but they are important, in connection with such observations, as failing to prove 

 that the blood is either cooled or heated in the lungs. From these facts it appears that 

 there is no positive evidence of any change in the temperature in the blood in passing 

 through the lungs in the human subject. In animals there probably exist no constant 

 differences in temperature in the two sides of the heart. When the loss of heat by the 

 general surface is active, as in animals with a slight covering of hair, the blood is gener- 

 ally cooler in the right cavities ; but, in animals with a thick covering, that probably lose a 

 great deal of heat by the pulmonary surface, the blood is cooler upon the left side. There 

 can be no doubt that there are refrigerating influences in the lungs, both from the low 

 temperature of the inspired air and from evaporation ; but these are equalized and some- 

 times overcome by processes in the blood itself, although, as we shall see hereafter, the 

 lungs are by no means the most important organs of calorification. 



Variations at Different Periods of Life, The most important variations in the tem- 

 perature of the body at different periods of life are observed in infants just after birih. 

 Aside from one or two observations, which are admitted to be exceptional, the body of 

 the infant and of young mammalia and birds, removed from the mother, presents a dimi- 

 nution in temperature of from one to nearly four degrees. In infancy the ability to resist 

 cold is less than in later years ; but after a few days the temperature of the child nearly 

 reaches the standard in the adult, and the variations produced by external conditions are 

 not so -great. 



The experiments of "W. F. Edwards have an important bearing upon our ideas of nutri- 

 tion during the first periods of extra-uterine life. He found that, in certain animals, 

 particularly dogs and cats, that are born with the eyes closed and in which the foramen 

 ovale remains open for a few days, the temperature rapidly diminished when they were 

 removed from the body of the mother, and that they then become reduced to a condition 

 approximating that of cold-blooded animals; but, after about fifteen days, this change in 

 temperature could not be effected. In dogs just born, the temperature fell after three or 

 four hours' separation from the mother to a point but a few degrees above that of the 

 surrounding atmosphere. The views advanced by Edwards are fully illustrated in in- 

 stances of premature birth, when the animal heat is much more variable than in infants 

 at term, and in cases of persistence of the foramen ovale. In certain instances in which 

 life has been prolonged under this abnormal condition, the individual is nearly in the 

 condition of a cold-blooded animal. We can also understand the remarkable power of 

 resistance to asphyxia in newly-born animals, for it is well known that cold-blooded ani- 

 mals will bear deprivation of oxygen much better than the higher classes. 



In adult life there does not appear to be any marked and constant variation in the 

 normal temperature ; but, in old age, according to the observations of Davy, while the 



