Some nineteenth-century pioneers of haematology.

IN THE course of the nineteenth century, the foundations of our modern understanding of the blood were laid. The part played by the cell in the body's economy was worked out, particularly by Virchow,1 and this permitted a rational understanding of the nature and role of blood cells. Technological advances such as the refinement of microscopes and the development of staining techniques enabled the morphology of the three formed elements of the blood to be described precisely, both in health and disease. Quantitative methods of blood examination were devised including techniques for counting erythrocytes and leucocytes and for determining the iron concentration, oxygen and carbon monoxide capacity and haemoglobin content. Variations in the ratio of haemoglobin content to red-cell numbers in disease were studied and the correlation of these variations with morphological changes in the cells were defined. Classical descriptions of a number ofhaematological syndromes were published. It was, in fact, an exciting period in the development of haematology as well as of medicine as a whole. However, I do not propose to tell here the history of the discoveries themselves. My purpose is to tell the stories of a select few of the many hundreds of people who made significant contributions to haematology in the nineteenth century. Naturally, any such selection is a matter of personal judgment and preference and I have chosen those workers whose contributions lay in general haematology and in the laboratory study of blood rather than those who described specific haematological syndromes. One other factor has influenced the selection. Preference has been given to those whose contributions to haematology are less well known but equally praiseworthy, rather than to those about whom a great deal has been written. For convenience, I have grouped the various people to be discussed according to their nationalities and as it was the French group who first studied the blood on a large scale, it is with workers from that country that we shall begin.