Paleopathology : an introduction to the study of ancient evidences of disease / by Roy L. Moodie.

  • Roy Lee Moodie
Date:
1923
Catalogue details

Licence: In copyright

Credit: Paleopathology : an introduction to the study of ancient evidences of disease / by Roy L. Moodie. Source: Wellcome Collection.

    41/890 (page 35)
    been as regards disease. At any rate the paleontological evidences are not wholly substantiated by conditions found in modern forms. The immunity among Paleozoic invertebrates may be apparent, only based on insufficient data, or it may be the correct status of affairs. The conclusions of observations so far made point to the latter being true. Metchnikoff has called attention to the occurrence of epidemics of a severe nature among protozoa, such as diseases in Amoebae caused by the Microsphaera and the disease in Actinophrys attributed to fungi allied to the genus Pythium. Pasteur’s studies on the pebrine and fla- cherie of the silkworms will be remembered as instances of severe epidemics in an invertebrate group. Molluscs, however, are appar-. ently largely immune to infection. Since the molluscous animals formed such a large percentage of the preserved faunas of the early periods of the earth’s history we may attribute our ignorance of the presence of disease to this factor, in part at least. The immunity of many inter¬ mediate hosts to infection is well known. The classical example of the mosquito-borne infections will suffice, although it is well known that insects of many kinds are subject to fatal diseases. Kowalevsky has discussed the anthrax of crickets and many other students have studied the problem. The entire question of immunity in its relation to all forms of extinct animals is of course a new and unsolved problem. But it seems certain that if the early animals were diseased, the ensuing pathology was of such a nature as to leave no impress upon the fossil¬ ized part; or else we have not yet learned to recognize these lesions. THE ORIGIN OF DISEASE Disease doubtless began wdth the inception of antagonism between two forms of life, and this may have occurred as early as the Archeo¬ zoic, and disease thus be as old as life itself. The evidences thus far seen point to a benign antagonism only late in the Paleozoic. If this is true the early faunas were free of disease. Phagocytosis began, with¬ out doubt, very early in the history of animal life. It is probable that the natural immunity of the early animals was sufficiently strong to resist the invasion by any pathogenic organisms in sufficient num¬ bers to produce disease. The breaking down of this immunity may possibly be correlated with the development of senescence22 among the 22 The studies of Charles Emerson Beecher (1856-1904), an American paleontologist, upon evolutionary phases of the early fossil brachiopods and trilobites are especially important to a consideration of the question of race senescence and the extinction of animal groups. His papers have been collected into a volume: “Studies in Evolution,” New York, 1901. The entire subject of senescence in the recent lower animals is discussed by Child in “Senescence and Rejuvenescence” ETniversity of Chicago Press, 1915.