A mechanism for organic correlation / G.H. Parker.

  • Parker, G. H.
Date:
1909
Catalogue details

Licence: In copyright

Credit: A mechanism for organic correlation / G.H. Parker. 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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    describes this principle as an unknown law of growth. It is to this aspect of the subject that I wish to direct your attention. Only a superficial acquaintance with organisms is needed to make one familiar with many examples of cor- relation. A hairy integument is always associated with mammary glands; albinism in fur and skin is accom- panied with a red color in the eye; and many other ex- amples of correlated characters might be given. The question that we have to consider is the nature of the association in correlated characters and much light can be thrown upon this, I believe, by a study of the ductless glands. The ductless glands such as the thyroid, the suprarenal bodies and the hypophysis of the brain were originally supposed to be functionless, but recent work has shown them not only to be functional but absolutely essential to the continuance of life. The removal of the supra- renal bodies from a mammal is invariably followed by death within a few hours and the loss of the hypophysis or the thyroid is also fatal though only after a somewhat longer interval. It is thus quite evident that these or- gans are of vital importance and that the continuance of life is dependent upon their presence. But they are not only necessarj^ for life; they profoundly influence the form and structure of the organism in which they occur. This is best seen in the case of the thyroid. In extreme disease of this gland or after its removal in the higher mammals, the skin thickens and thus produces a mis- shapen aspect in the features and the extremities, there is a tendency to the loss of hair, and the nervous organs are so affected that the animal sinks into a condition of semi-idiocy (cretinism). Thus there are not only funda- mental internal changes, but the external features such as a naturalist might use in describing a species are pro- foundly modified. Certain external features, then, in the normal animal are correlated with the state of the thyroid and, as disease and experiment show, they fluctu-