July 2, 1915] 



SCIENCE 



hygiene fathered by him made a profound 

 impression upon Europe, especially upon 

 Germany and Austria. Professorships were 

 established in the leading medical schools, 

 first in Bavaria and then in other parts of 

 the German empire, thoroughly trained 

 men were put in charge of the administra- 

 tion of sanitary laws and the attempt made 

 to limit the spread of the infectious dis- 

 eases by scientific methods. The new knowl- 

 edge acquired by Pettenkofer and his 

 pupils, and the laws promulgated at their 

 suggestion soon began to have a definite in- 

 fluence upon the mortality returns. Jn the 

 city of Munich, for instance, the sewage 

 system was reconstructed and proper meth- 

 ods established for drawing off human and 

 animal wastes, a new and pure supply of 

 drinking water was obtained, old, ill-con- 

 structed houses were pulled down and air 

 and sunshine admitted to the darkest sec- 

 tions of the city. A special corps of sani- 

 tary police was instituted, the members of 

 which were given extraordinary powers so 

 that they could visit every quarter of the 

 city, and enter every dwelling to enforce 

 the execution of the new sanitary laws. As 

 a result of these sweeping changes the mor- 

 tality from zymotic diseases fell rapidly in 

 Munich and typhoid fever practically dis- 

 appeared. In Vienna also, where Gruber, 

 a pupil of von Pettenkofer, became pro- 

 fessor of hygiene in the university, a sim- 

 ilar change took place. Here was a city 

 built within narrow walls, the population 

 crowded together in unsanitary quarters 

 with a water supply from surface wells 

 sunk in a sewage-permeated soil. Sweeping 

 reforms were instituted in this old medieval 



laboratory, study the chemical composition of 

 drugs, determine their action by animal experimen- 

 tation and endeavor to explain this action by the 

 facts and theories of physiology. Under the lead- 

 ership of Schmiedeberg the new science of pharma- 

 cology was established to take the place of the 

 older science of therapeutics. 



town, a new method of sewage disposal 

 established, a new water supply obtained 

 and in a surprisingly short time the typhoid 

 mortality was cut in two. Whereas in 1874 

 it had been 15-16 per thousand, by the end 

 of two years it had fallen to 7-8 per thou- 

 sand and subsequently steadily diminished. 



Under the stimulus of von Pettenkofer 

 the new science of hygiene developed 

 rapidly and from his institute in Munich 

 his pupils passed first to one and then to 

 another of the European universities as the 

 chairs of hygiene were founded. Thus 

 Buchner became associated with hygiene 

 in Munich, Gruber went to Vienna, von 

 Podor to Budapest, Fliigge to Gottingen 

 (later to Breslau), Hofman to Leipzig, 

 Lehmann to Wiirzburg, Rubner to Mar- 

 burg, Pfeiffer to Rostock and Prausnitz to 

 Gratz. The science of hygiene was estab- 

 lished upon a firm basis and it is not too 

 much to say that the movement inaugu- 

 rated by von Pettenkofer was one of the 

 most important movements in the science 

 of medicine of the nineteenth century. 



The Munich school of hygiene was devel- 

 oped in the days before modern bacteriol- 

 ogy was dreamed of however, the etiological 

 agents of disease were unknown and much 

 of the work of the great investigators had 

 to be carried out upon a hypothetical basis. 

 This is best shown by the famous x y z 

 hypothesis of von Pettenkofer by means of 

 which he attempted to explain the spread 

 of the diseases in which the intestinal tract 

 is involved, typhoid fever, cholera and 

 dysentery, the so-called diseases of the soil 

 or Bodenkrankheiten. The kernel of this 

 hypothesis lay in von Pettenkofer 's belief 

 that the unknown etiological agents of these 

 diseases must undergo a process of modifi- 

 cation or ripening in the soil before they 

 are in a condition to produce the disease in 

 other individuals. With the rise of the 

 new science of bacteriology as the result of 



