14 FIXED STANDAEDS OF PHYSIOLOGY. 



stance, under low and high aerial temperatures, change of atmospheric 

 pressures, absolute quiescence, or the near approach thereto, the effect of 

 a determined amount of locomotion, or other muscular exertion, &c. As 

 the science becomes more perfect, it should likewise attempt to embrace 

 pathological states ; as, for instance, the diurnal or periodic production of 

 heat in fevers, the effect of the hygienic system of the bedroom. 



Physiology having attained to this high condition, the practice of med- 

 icine in its great department of diagnosis will consist, in reality, in the 

 solution of inverse problems. Given the variations from the standard ex- 

 isting in any case, to determine the cause of those variations. At this 

 point diagnosis becomes a science, and ceases to be an art. 



As in painting and statuary, the artist has an ideal model in his mind, 

 Illustration of a ^7P^ ca ^ standard which no living being has perfectly reach- 

 the following ed, though some of the most beautiful may have approached 

 thereto, so in physiology the standard or typical man pre- 

 sents the combined and mean values of all the human race. 



A less comprehensive view presents us with distinct national standards, 

 instead of this universal one, for every country has its own peculiarities. 

 Eesults of the highest interest are to be perceived when these national 

 standards are compared with one another. Even the same nation must 

 offer, from age to age, modifications in its type expressive of the secular 

 perturbations it is undergoing, as it advances or descends in a knowledge 

 of the arts of life and civilization. 



Moreover, there are typical standards of a still lower order, having ref- 

 erence to the conditions of sex and the period of life. Of these six may 

 be designated the infant, the adult, the aged, of the male and female sex 

 respectively. 



As illustrations of these remarks, and examples of the determination of 

 the fundamental element of such a general physiological table, the stand- 

 ard weight of the body, we may take the following estimates. An ex- 

 amination of 20,000 infants, at the Maternite in Paris, gives for the weight 

 of the new-born 6 Jibs. ; the same mean value obtains for the city of Brus- 

 sels. For about a week after birth this weight undergoes an actual dim- 

 inution, owing to the tissue destruction which ensues through the estab- 

 lishment of aerial respiration, and which for the time exceeds the gain 

 from nutrition. For the same age the male infant is heavier than the fe- 

 male, but this difference gradually diminishes, and at twelve years their 

 weight is sensibly the same. Three years later, at the period of puberty, 

 the weight is one half of what it is finally to be, when full development 

 is reached. The maximum weight eventually attained is a little more 

 than twenty times that at birth, this holding good for both sexes ; but 

 since the new-born female weighs less than the standard, and the new- 

 born male more, the weight of the adult male is 136^^- Ibs., and of the 



