684 



GENERAL REVIEW OF THE NUTRITIVE PROCESSES. 



We see from this table that, during the first month of infant life, the external temperature 

 has a very marked influence; for the average mortality during each of the three summer 

 months being 80, that of January is nearly 140, and the average of February and March is 

 125. This is confirmed by the result obtained by MM. Villerrne and Milne-Edwards, in 

 their researches on the mortality of the children conveyed to the Foundling Hospitals in 

 the different towns in France ; for they not only ascertained that the mortality is much the 

 greatest during the first three months in the year, but also that it varies in different parts of 

 ilie kingdom, according to the relative severity of the winter. As childhood advances, how- 

 ever, the winter mortality diminishes, whilst that of the spring undergoes an increase; this 

 is probably due to the greater prevalence of certain epidemics at the latter season ; for the 

 same condition is observed, in a still more remarkable degree, between the ages of S and 12 

 years, the time when children are most severely affected by such epidemics. As the con- 

 stitution acquires greater vigour, and the bodily structure attains its full development, the 

 influence of the season upon mortality becomes less apparent; so that at the age of from 

 25 to 30 years, the difference between the summer and winter mortality is very slight. This 

 difference reappears, however, in a very marked degree, at a later period, when the general 

 vigour, and the calorifying power, undergo a gradual diminution. Between the ages of 50 

 and 65 it is nearly as great as in early infancy ; and it gradually becomes more striking, 

 until, at the age of 90 and upwards, the deaths in January are 158, for every 04 in July (a 

 proportion of 2^ to ]); and the average of the three winter months is 145, whilst that of 

 the three summer months is only 68, or less than one-half. 



894. Not only does the same individual possess different degrees of calori- 

 fying power, at different periods of his life, but also at different seasons of 

 the year. 



a. Dr. Edwards found that Sparrows, when exposed for some time to a temperature of 

 32 during the summer, rapidly lost heat, the refrigeration during 3 hours being from 6 to 

 21 degrees ; but that, when they were placed in the same circumstances during winter (after 

 having been accustomed to a warm temperature) the refrigeration was much less, not being 

 in any instance more than 2 in 3 hours. Although it would be difficult to prove the fact 

 experimentally in regard to Man, there can be little doubt that he shares with the other 

 Mammalia in this variation. It is well known that the general vigour of the system is less 

 in summer than in winter; in hot climates than in moderately cold. Moreover, we con- 

 tinually experience the great discomforts of a eold day in summer; when, our system not 

 being prepared for it, we can less readily maintain our temperature at its normal standard. 

 The practical inference, that we should bo much on our guard against exposure to low 

 temperatures during summer, is one of much importance'; and its value has been fully 

 confirmed by experience. The same principle may also be applied to the explanation of 

 the well-known fact, that those who have been long resident in warm climates fuel the cold 

 acutely; whilst those who have been inured to cold are able to resist it much better, than 

 those who arc' exposed to it for the first time. The former have a continued summer con- 

 stitution; and their system not being called upon by its external conditions to produce much 

 heat, the power is after a time partially lost. On the other hand, those who live in cold 

 climates have a perpetual iriiilrr constitution (as it were) established; and the amount of 

 heat generated by them is much greater. It will be obvious that this must be the case, if 

 Man's capability of living under the greatest varieties of climate be sufficiently considered. 

 From Dr. E.'s experiments it appears, that every month makes an evident difference in the 



