Page:The advancement of science by experimental research - the Harveian oration, delivered at the Royal College of Physicians, June 27th, 1883 (IA b24869958).pdf/51

 the altered states of its muscular fibre, we have learnt not only the true nature of the sounds of the heart, but the import of their morbid changes; the sphygmograph and cardiograph have led to as much accuracy in clinical observation, as the use of the thermometer has done in the study of febrile conditions. The discoveries in the physiology of the brain and the whole nervous system have explained the facts of pathological science; but it has been a gradual evolution of truth. In no branch of medical science have greater advances been made, than in the knowledge of the diseases of the spinal cord and of the whole nervous system.

During the last few years a comparatively unexplored field of research has been laid open, which is now being pushed forward with determined zeal, the study of the morbid germs and their connection with the etiology of disease. The bacteria are now regarded as the actual or the proximate causes of many maladies; they are the simplest forms of vegetable life, and arc classified according to their