| 75.6 | 1670 | 22.1 | | 82.0 | 1556 | 19.0 | | 82.7 | 2030? | 24.5 | | 83.5 | 1670 | 20.0 | | 88.3 | 2019? | 22.9 | | 90.4 | 1773 | 19.6 | +-------------+----------------+--------------+ As Richet has expressed it, the basal energy exchange is inversely proportional to the body-weight and directly proportional to the body surface. This is in harmony with the view advanced by v. Hösslin, “that all the important physiological activities of the body, including of course its internal work and the consequent heat production, are substantially proportional to the two-thirds power of its volume, and that since the external surface bears the same ratio to the volume, a proportionality necessarily exists between heat production and surface.”[35] [35] See Armsby: Principles of Animal Nutrition, p. 368. There are, however, many circumstances that modify, or influence, energy exchange. Thus, the taking of food, with all the attendant processes of digestion, assimilation, etc., involves an expenditure of energy not inconsiderable. This has been experimentally demonstrated on man by several investigators. With fatty food, Magnus-Levy found that his subject lying upon a couch, as completely at rest as possible, produced in the 24 hours 1547 calories when 94 grams of fat were eaten, and 1582 calories when 195 grams of fat were consumed. The increase of heat production over the basal energy exchange was 10 and 58 calories respectively. With a mixed diet, where proteid food is a conspicuous element, the increase in heat production is much more marked. Thus, in some experiments reported from Sweden the following data were obtained:[36] [36] Taken from Armsby: Principles of Animal Nutrition, p. 383. +---------+---------------------+------------------+ | Day. | Energy of the Food. | Heat Production. | +---------+---------------------+------------------+ | | calories | calories | | First | 4141 | .... | | Second | 4277 | 2705 | | Third | 0 | 2220 | | Fourth | 0 | 2102 | | Fifth | 0 | 2024 | | Sixth | 0 | 1992 | | Seventh | 0 | 1970 | | Eighth | 4355 | 2436 | | Ninth | 3946 | 2410 | +---------+---------------------+------------------+