50 THE KIDDLE OF THE UNIVERSE. 



vital functions. Particular schools of medicine, the 

 Iatrophysical and the Iatrochemical, had already in 

 the seventeenth century attempted to trace the sources 

 of disease to certain physical and chemical changes. 

 However, the imperfect condition of science at that 

 period precluded any lasting result of these efforts. 

 Many of the older theories, which sought the nature 

 of disease in supernatural and nrystical causes, were 

 almost universally accepted down to the middle of the 

 nineteenth century. 



It was then that Eudolf Virchow, another pupil of 

 Miiller, conceived the happy idea of transferring the 

 cellular theory from the healthy to the diseased 

 organism ; he sought in the more minute metamor- 

 phoses of the diseased cells and the tissues they 

 composed the true sources of those larger changes 

 which, in the form of disease, threaten the living 

 organism with peril and death. Especially during 

 the seven years of his professorship at Wiirzburg 

 (1849-56) Virchow pursued his great task with such 

 brilliant results that his Cellular Pathology (published 

 in 1858) turned, at one stroke, the whole of pathology 

 and the dependent science of practical medicine into 

 new and eminently fruitful paths. This reform of 

 medicine is significant for our present purpose in that 

 it led to a monistic and purely scientific conception 

 of disease. In sickness, no less than in health, man 

 is subject to the same " eternal iron laws " of physics 

 and chemistry as all the rest of the organic world. 



Among the numerous classes of animals which 

 modern zoology distinguishes the mammals occupy 

 a pre-eminent position, not only on morphological 

 grounds, but also for physiological reasons. As 

 man belongs to the class of mammals (see p. 27) 



