244 INTRODUCTORY. 



chest, or abdomen. In fact, but little was added to the teach- 

 ings of Hippocrates (460 B. c.) and Galen (130-200 A. D.) 

 until about 1500, when the first post-mortems began to be 

 made. 



During the sixteenth century Vesalius, Sylvius, and their 

 successors laid the foundation of modern medicine by the 

 systematic study of anatomy, to which was added by Harvey 

 and others during the seventeenth century such essential 

 physiological data as the function of the heart, circulation of 

 blood, and the mechanism of respiration. 



Morgagni (1682-1771) was the first to attempt to localize 

 a disease-process in a particular organ and wrote the first 

 great treatise on morbid anatomy. The first illustrated work 

 on the subject was by Baillie (1799), who drew his inspiration 

 and material from John Hunter. It was not until the early 

 part of this century, however, that there was a real beginning 

 in its study. But there were limitations to gross morbid 

 anatomy. 



Histology received its first impulse from Bichat, to whom 

 is due also a step in advance in pathology ; he declared that 

 the ultimate seat of a disease might be a particular tissue 

 of an organ. Though the microscope had been employed 

 in the seventeenth century by Leuweenhoeck and Malpighi, 

 it was as recent as 1847 that the foundation of normal his- 

 tology was laid by the work of Schleiden on "Vegetable 

 Pathology/' and later of Schwann on the " Comparison of 

 the Cellular Structure of Vegetables and Animals." 



Modern or cellular pathology dates from the teachings of 

 Virchow (1858), to whom credit is due, more than to any 

 other one man, for elevating the study of disease to a place 

 in the science of biology. The cellular theory of life led 

 naturally to the cellular theory of disease. A comparison of 

 the lower forms of animal and vegetable life with the cells 

 of higher ones convinced Virchow that if the former are in- 

 dividuals, the latter must be so regarded also. For the axiom 

 of Harvey, "Omne vivum ex ovo," he substituted the dictum 

 " Omnis cellula a cellula " ; he applied the histological dis- 

 coveries of Schleiden and Schwann to pathology and showed 

 that the essence of disease is the altered cell, the histological 

 and vital unit of all organized tissue, and called attention to 



