De Globulis Sanguinis, Colore Et Qualitatibus (1650-1860) *

Doubtless early man gazed with wonder on the brightly flowing blood whose loss meant death to prey, or foe, or friend. This connection of blood with life is nowhere more clearly expressed than in the reiterated prohibitions of the Mosaic law, as: "Only be sure that thou eat not the blood: for the blood is the life; and thou mayest not eat the life with the flesh" (Deuteronomy xii:23). Hippocrates, too, endowed this fluid with special properties; however, he considered it little more important than other fluids in the body. In the first century B. C., Aristotle viewed the blood with some scientific interest; he used it as a basis for classifying animals into sanguineous and bloodless. Galen's humoral concept of physiology, with the blood as one of the controlling factors in the nature of man, was retained along with the rest of his medical philosophy; indeed, we are prone even today to speak of a person as of a "sanguine" temperament. The alchemists, in their fumbling search for the philosopher's stone, examined the blood, but their results had little lasting import. Though the blood as the stream of life had thus long been an object of interest and speculation, not until the late seventeenth century was it examined by discerning eyes and its structure seen to be not a homogeneous red liquid, but a clear fluid containing myriads of pale yellow discs. It was in 1658 that Swammerdam'32, then just twenty-one years old, first observed and described the red corpuscles. Unfortunately, a few years later he joined a religious cult which considered scientific inquiry vain and fruitless; therefore, much of his work was not published until after his death. (It is to be noted, however, that his inaugural dissertation, Tractatus, Physico-Anatomico Medicus de Respiratione usuque Pulmonum, delivered at Gottingen, in 1667, made no mention of red corpuscles.) On account of Swammerdam's obscurity the discovery of the red corpuscles has been attributed to Marcellus Malpighi, the discoverer of the capillaries. Probably Malpighi did not realize the importance of his observations' for, while investigating fat deposits, he wrote98: "And I myself in