The ductless glands as a factor in the production of racial differences / by Antonio M. Crispin.

  • Crispin, Antonio M.
Date:
1912
Catalogue details

Licence: In copyright

Credit: The ductless glands as a factor in the production of racial differences / by Antonio M. Crispin. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    It is also a well-established fact that these glands exert a powerful influ- ence on the nervous system, especially the thyroids and parathyroids, although their actions are different. Kemoval of the parathyroids increases galvanic irritability. This may be explained by the loss of calcium, as calcium decreases the irritability of the cerebrospinal axis. Other glands and organs possess the power of influencing the body through the agency of an internal secretion, e.g., the testicles and ovaries. The de- pendence of the secondary sexual characters on the internal secretions of these organs is a well-established fact. Another interesting point, but little understood, is the mutual relation of these various internal secretions, e.g., the relation of the hypophysis to the secretion of the thyroids or to that of the essential sexual organs, or the mutual relation of the internal secretions of the pancreas, adrenals, and thyroids, which constitutes an unsolved problem. These ductless glands discharge into the circulation specific hormones, and probably play an important role in the production of immunity. Caution is, of course, needed in interpreting these interesting phenomena, but when we consider the functions of these glands, and their vital importance to the organism, we cannot but be impressed by their apparent value in the determination of adaptability and consequently in the production of the dif- ferent races of mankind. Excessive pigmentation may be due to altered activity of the adrenal glands; of this we have sufficient evidence in the pathology of Addison’s dis- ease. May it not be that an excess of sunlight, combined with the well-known effect of altitude, has exerted a decided modifying action on the adrenal glands of the negroes? As regards the chemical power of light, advanced by von Schmaedel in 1895, it is held that the black pigment renders the skin of negroes insensitive to the luminous or actinic effects of solar radiation, which are far more destructive to living protoplasm than the mere calorific effects. Light tends to destroy any substance that absorbs it; man and animals develop there- fore, when needed, a protective armor of pigment. Altitude has operated in differentiating the inland people from those in- habiting the coast, and has exaggerated the ethnic peculiarities of given nations. The pigment of the skin tends, as a rule, to be lighter in the higher altitudes as well as in the higher latitudes. The influence of these two factors on the suprarenal bodies would appear to be the same. In the case of the excessive pigmentation of the negro, we are told that his dark skin is associated with a dense cuticle, diminished perspiration, smaller chest volume, and less respiratory power, together with a lower tem- perature and more rapid pulse. Compare this with the symptoms observed in Addison’s disease or when extracts of the adrenal gland have been administered medicinally or experimentally, and the similarity of action will be evident. The effect of temperature is very marked not only on the body in general, but on the growth of the hair in particular. A low temperature is apt to result in the formation of a good protective coating, while a high temperature acts in the opposite way. High temperatures reflexly stimulate the adrenal