32 MEDICINE 



periments. He carried the anatomic study of disease further than 

 ever before, endeavoring to ascertain not only the lesions in the 

 organs, but in the tissues which compose them. The relation be- 

 tween the anatomic lesions and disorders of function he says must 

 be studied by experiment. The work of Magendie in physiology 

 was hardly less important than that of Bichat in pathology. Phy- 

 siology had suffered from the theory of vital force which as a seeming 

 explanation weighed upon it as an incubus, opposing investigation. 

 He claimed for physiology the same methods as in physics and 

 chemistry, saying that the carefully conducted experiment is alone 

 decisive in testing the conclusions formed from observation of phe- 

 nomena. The work of Magendie had full recognition in France, 

 and he was followed by Claude Bernard and Brown-Sequard, who 

 further developed his methods. Corvisart, Andral, Louis, Rayer, 

 and Cruvilhier were among the most brilliant men in the new school 

 which was founded by Bichat and Magendie. Corvisart and Laennec 

 deserve especial mention in that the former brought to general 

 knowledge the method of percussion of Auenbrugger, which had 

 been forgotten, and the latter introduced and further developed the 

 method of auscultation. 



In the advance of science new technical methods of investigation 

 play a most important role. The technical method enables the 

 observation to extend further and more deeply. Virchow has said 

 that the introduction of the microscope into medical research en- 

 abled us to approach several hundred times nearer disease than 

 before. The microscope introduced a new era in the study of disease ; 

 it came into general use when the study of gross pathology in the 

 absence of new questions had almost reached its limit. It gave more 

 correct ideas of disease by increasing the powers of observation; it 

 overthrew at once many theories and gave new points of view and 

 new questions, from which further observation could proceed. 

 Every improvement in the microscope by which its efficiency is 

 increased has the same influence. The knowledge of the influence 

 of bacteria in disease is due, in the first instance, to the improve- 

 ment of the microscope, and in the second, to the discovery by 

 Koch of methods of cultivation, by means of which the individual 

 species can be studied. Until this was possible our knowledge of 

 bacteria was inexact and their causative relation to disease only 

 an hypothesis. The development of knowledge of the minute struc- 

 ture of cells and tissues is principally due to the use of methods of 

 staining, which started with the simple carmin stain of Gerlach. In 

 clinical medicine the introduction of the microscope, the thermo- 

 meter, the methods of chemic investigation, the blood-counter, the 

 Rontgen ray, have all led to a closer insight into disease and the 

 substitution of knowledge for conjecture. There is a further indirect 



