University of the Pacific School of Dentistry - Chips Yearbook (San Francisco, CA)

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growth or development, and decay. It is universally admitted that human life begins with a single cell, the ovum. This is fertilized by another single cell, the spermatozoon. Each of these single cells is com- posed of protoplasm containing '75 to S5 per cent of water and 25 to 15 per cent oflproteids Calbuminsj made up of carbon, hydrogen, nitrogen, oxvgen, sul- phur, and phosphorus, and a nucleus largely made up of nuclein, a phosphor-proteid compound. The essence of life, from a physical, physiological, and anatomic basis would seem to reside in this Hgerminal matter called nucleated protoplasm. At all events, each cell is a unit of life, both anatomically and physiologically, and the phenomena of life are ext- hibited in these cells, whether the organism is uni- cellular, such as the ameba, or multicellular, such as the complex organism called man. At first the em- bryonic or primitive cells are nearly all alike, but they early exhibit the same life phenomena that their parent cells possess, viz., multiplication or pro- liferation and morphosis or differentiation Ccytomor- phosisj. Cells multiply by the well-known processes of karyokinosis, mitosis and akinesis, amitosis, indi- rect and direct cell division, until we see them arranged into three distinct layers of differention cells or tissues in the embryo, known as the ectoderm or epiblast, mesoderm or mesoblast, and endoderm or hypoblast-the blasto-dermic or germ layers from which develop the whole complex human body from a single cell. From the ectoderm or epiblast develop the skin, nervous system, and the sense organs, etc.: from the mesoderm, the skeleton, muscles, heart, blood-vessels, etc., from the endoderm, the epithelium of the alimentary canal, chief glands, etc. The human body is thus composed of multicellular differentiated structures, skin, muscle, bone, nerves, vessels, special organs, etc., etc. The Cause of Senescence Arterial Degeneration.-According to one theory of I9

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DR. WINSLOW ANDERSON

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the wise men of the East, it is vascular degenera- tion. Professor Osler says: Longevity is a vascular question and has been well expressed in the axiom, 'A man is only as old as his arteriesf 'l Arterio-sclerosis is a favorite or popular theory of senility, but when it is remembered that many ani- mals of the lower forms of creation have no arteries to grow hard and sclerotic, we see that Osler and popular theories will not entirely satisfy scientific inquiry. Atrophy.-Another theory of senescence, cham- pioned by no less an authority than that of the direc- tor of the l:'asteur Institute at Paris, Professor Metch- nikoff, claims that old age is due to atrophic changes in the tissues of the body, b1'ain, nerve ganglion, muscles, bone, etc. W'e know the brain loses an ounce in weight each year alter 60. We also lcnow that with senility goes physiological as well as ana- tomical deterioration. Auto-intoxication.-This plausible theory claims that senescence is due to self-poisoning. Professor 'l'. Il. M.ontgomery, jr., maintains that death results from an accumulation of waste products in the tis- sues-insufficiency of excretion of morbihc products. Fermentation Toxines.--The fermentation explana- tion of old age assumes that as we grow old thc tendency to colonic fermentation increases and that bacterial and chemic poisons, toxines, are produced which inhibit normal cellular regeneration and induce necrobiosis or cell degeneration and disintegration, resulting in senescence and finally in death. Phagocytosis.-The theory of phagocytosis causing senility and ultimately death is based upon the observation that phagocytes Ceating cellsj will devour noxious or diseased cellular tissue to rid the body of contamination. Similarly, it is argued, when cellular structures are weakened by,disease, or toxins, or bac- terial invasion, or atrophic degeneration, these cell destroyers consume, eat up, and disintegrate and absorb the cells of which the body is composed to 20