1004 



SCIENCE. 



[N. S. Vol. XVI. No. 417. 



worthy rank among the great men of medi- 

 cine of the nineteenth century, for few 

 books exercised a greater influence over 

 medicine during that period than his 'Cel- 

 lular Pathology.' From ancient times 

 physicians had been divided into many 

 camps regarding the cause of disease. One 

 idea had been prominent for more than 

 twenty centuries: The humoralists had 

 maintained that pathological phenomena 

 were due to the improper behavior or 

 admixture of the liquids of the body, which 

 were, in the original form of this theory, 

 the four humors: blood, phlegm, yellow 

 bile and black bile. According to the 

 solidists, on the other hand, the offending 

 agents were not the liquids but the solids, 

 and especially the nervous tissues. Both 

 humoralists and solidists were excessively 

 speculative, and the gx-owing scientific spirit 

 of the nineteenth century was becoming 

 impatient of hypotheses that could not be 

 experimentally proved. The times were 

 ripe for new ideas. Virchow, soon after 

 taking the professor 's chair at Berlin which 

 he held from 1856 until his death, gave to 

 an audience largely composed of medical 

 practitioners, the lectures which, more than 

 all else, have made him famous among his 

 professional brethren. His main thesis 

 was the cellular nature of all the structures 

 and processes, whether normal or patholog- 

 ical, of all organized beings, and his dictum, 

 ' omnis cellula e cellula' — a cell arises only 

 from an already existing cell is the key- 

 note of his theories. With his microscope 

 he demonstrated the cells in all the tissues 

 of the body, whether normal or patholog- 

 ical, and he proved the origin of the morbid 

 cells in the normal ones. As to processes, 

 he maintained rightly that all parts of the 

 body are irritable, that every vital action 

 is the result of a stimulus acting upon an 

 irritable part, and he claimed a complete 

 analogy between physiological and patho- 



logical processes. Every morbid struc- 

 ture and every morbid process has its nor- 

 mal prototype. 



Virchow 's ideas aroused enthusiasm the 

 world over, and were eagerly studied and 

 largely accepted by progressive men of 

 medicine. Time and research have cor- 

 rected errors of detail, but no one now 

 denies the cellular nature and physiological 

 basis of pathological phenomena. These 

 facts are fundamental to the understand- 

 ing and treatment of disease, which is now 

 universally regarded as the behavior of 

 the body cells under the influence of an in- 

 jurious environment. 



Virchow 's ideas regarding pathological 

 formations are a fitting complement to the 

 laws of the conservation and transforma- 

 tion of energy. In the living world, as in 

 the non-living, the law of continuity holds 

 good. There are no cataclysms, there is 

 no new creation. Striicture and energy, 

 whether normal or abnormal, proceed from 

 preexisting structure and energy. Only 

 such a conception can make possible a sci- 

 entific medicine, and, since its promulga- 

 tion, medical advance has been rapid. 



Tlie Rise of Bacteriology.— During the 

 past half-century, and largely during the 

 past twenty-five years, that is, during the 

 lifetime of this university, there has grown 

 up a totally new science, comprising a vast 

 literature and a vast subject matter, 

 though dealing Avith the most minute of 

 living things. This is the science of bac- 

 teriology. The achievements in this field 

 have surpassed all others in their striking 

 and revolutionary character, and bear both 

 on the conception of the nature of a very 

 large number of diseases, hitherto puzzling 

 human understanding, and on their pre- 

 vention and cure, hitherto baffling human 

 skill. All other human deaths are few in 

 number in comparison with those that have 

 been caused bv the infectious diseases. 



