AXD PREVENTION OF PHTHISIS. 399 



After the investigation of Koch, various questions 

 of moment pushed themselves imperiously to the front: 

 How is phthisis generated? How is it propagated? 

 What is the part played by the air as the vehicle of 

 tubercle bacilli? How are healthy lungs to be pro- 

 tected from their ravages? What value is to be as- 

 signed to the hypothesis of predisposition and hereditary 

 transmission? Cornet describes the attempts made to 

 answer these and other questions. The results were 

 conflicting, and when subjected to critical examination 

 they were proved, for the most part, inadequate and 

 inconclusive. The art of experiment is different from 

 that of observation; so much so, that good observers 

 frequently prove but indifferent experimenters. It was 

 his education as an experimenter that gave Pasteur 

 such immense advantage over Pouchet in their cele- 

 brated controversy on " spontaneous generation " ; and 

 it is on the score of experiment that the writers ex- 

 amined by Cornet were found most wanting. One 

 evil result of this conflict of opinions as to the propa- 

 gation and prevention of phthisis, was the unwarrant- 

 able indifference which it generated among medical 

 men. 



The researches referred to and criticised by Cornet 

 are too voluminous to be mentioned in detail. Valuable 

 information was, to some extent, yielded by these re- 

 searches, but they nevertheless left the subject in a 

 state of vagueness and uncertainty. Cornet, in fact, 

 when he began his inquiry, found himself confronted 

 by a practically untrodden domain. He entered it with 

 a full knowledge of the gravity of his task. The result 

 of his investigation is a memoir of 140 pages, the im- 

 portance of which, and the vast amount of labour in- 

 volved in it, can be appreciated by those only who have 

 read it and studied it from beginning to end. 



