154 THE GERM THEORY OF DISEASE. 



This acid was, of course, produced in the process of fermenta- 

 tion; but in the light of the developments of the last few 

 years, their observations seem vague and very indefinite. 

 They attributed this result to leptothrix buccalis. The ob- 

 servations upon which their views were based were given at 

 length ; so that we are able to follow them through all their 

 operations, and from the care with which these were con- 

 ducted, judge of the merits of their deductions from them. 

 When we pass their work in review carefully, we must admit 

 that it is wanting in that extreme care that is necessary in 

 investigations of this delicate nature; especially is this the 

 case when we examine the work in the light that succeeding 

 years have thrown upon investigations of this class. In fact, 

 the modes employed in such work have been completely 

 revolutionized since this work appeared ; and as the general 

 nature of such work has been discussed in a previous lecture, 

 and its progress described, it need not detain ns now. 



Notwithstanding the evident errors of the work of Lieber 

 and Rottenstein, it undoubtedly made a deep impression on 

 the thought of the dental profession ; and this question has 

 not been lost sight of for an instant. While the opinions 

 given were not accepted, and were, apparently, quickly dis- 

 proved, it lent an impetus to the study ; and though no great 

 work has appeared, it has been progressing in an intermittent 

 way, until now the profession seem to be ready to receive any 

 work on this subject that will bear reasonably rigid criticism. 

 Such a work is, fortunately, now appearing, from the pen of 

 Dr. Miller, who, though an American, is working in the 

 laboratory of Dr. Koch of Berlin. Dr. Miller is, fortunately, 

 in the very best position possible for the performance of this 

 difficult form of investigation ; and the papers that have 

 already appeared from his pen give much encouragement that 

 he will succeed in working out this subject, and in giving us 



