VI. 



RETROSPECT AND PROSPECT OF 

 PROGRESS. 



FOUK years have passed since the paper upon 

 "Some Problems of Bacteriology" was written. 

 Times change and we change with them, and such 

 change is no disgrace provided it consists in progress 

 towai'd truth. That during these four years modifi- 

 cations of views have come about, supposed facts have 

 been shown to be deceptive, new truths have come to 

 light and broader conceptions of matters bacteriolog- 

 ical have developed, goes without saying. 



It may, therefore, not be out of place to review 

 some of the statements contained in former essays, 

 that we may see how far modifications are necessary 

 to adapt these statements to present knowledge, and 

 how much nearer we have come to established truth. 

 As we proceed in this review it will become evidenc 

 that in some directions there has been a simplification 

 which is to be expected as the field clears and we come 

 nearer to the great and fundamental truths. 



In other directions progress has served but to show 

 into what an immense field we have entered. In 

 some directions final truth has been reached or is near 

 at hand; in others it is evidently as yet afar off. But 



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