respiration) will almost entirely cease, or will raise the blood two degrees above the natural standard (fever.) We have only to do with the former alternative. Combustion almost ceasing, there will occur no change in the blood: the particles which should have been thrown off by respiration, remain, and the unchanged blood, loaded with these effete particles, steadily depresses physical vigor.
Nature has partially provided against this high temperature, in granting to the people of the tropics a skin which contains an elaborate refrigerator:[1] for, the carbon or charcoal placed immediately beneath the cuticle in the dark complexioned portion of mankind is a non-conductor, which isolates the temperature of the body from that of the surrounding hot air. The temperature of the blood of the body, thus kept low until it enters the lungs, can be raised in the lungs by respiration: hence combustion measurable occurs; the effete particles are thrown off; the blood undergoes the requisite change; and physical vigor is to some extent developed.
Notwithstanding this provision, it is not possible that the intertropical races can have a physical vigor and development equal to those who dwell in a more temperate climate; First, because the air in the tropics for the most part, contains more vapor of water, and consequently less oxygen, than the air of the temperate regions: and as oxygen is the cause of combustion in the lungs, the smaller proportion of oxygen is accompanied by a less rapid combustion; and a smaller development of physical strength. Hence, the dark races in hot climates have flattened chests, from the relatively less exercise or expansion of their lungs in breathing.
Secondly, the dark races of the tropics gain in physical development when transported to a temperate climate. The colored population, enslaved and free, of Maryland and Virginia, are the descendants of those who, from 50 to 200 years ago, were removed from the African coast. This Afric-American race, are not only far superior, in physical symmetry and development, to pure Africans now found on the coast, but actually equal in these respects the white race of Old Dominion, who have never lived in any but a temperate clime. Facts indicate, further, that the excessively hot climate is more favorable to physical development, than an excessively cold climate. Having considered the extreme climates, return for a moment to the mean or temperate zone. Blessed with a climate neither too near, nor too far removed from, the independent temperature of the human body, the people of the middle latitudes enjoy the happy mean wherein respiration performs its functions with a well balanced relation to the ends which they subserve: there results a combustion sufficient to carry off the effete particles from the blood, and which leaves the same sufficiently enriched for a full and harmonious development of a vigorous physical frame.
But, what has physical development to do with civilization? It is true that civilization has originated, and made the greatest advances in the climate which produces the greatest physical vigor in mankind: but this may be mere coincidence, or may result from innate superiority in the races living in said climate. It is even a prevalent opinion that physical strength is a matter so distinct from and independent of intellectual power, that the presence of the one implies the absence of the other; thews and sinews, the bone and muscle of a country are abstractly regarded as widely distinct from the thought of
- ↑ Although during some days in habitable places, the thermometer continues above 130 deg. Fahr. no portion of the human race could endure this heat for a length of time. The highest mean annual temperature recorded is 87 deg. and the hottest month 91 deg.; at Masfaoua in Abyssinia. Even during the hottest month, the mean temperature was 7 deg. lower than that of the human body.
