AND CONTENTS OF THE MOUTH. 163 



In 1847 Robin thought that the principal micro-organism of 

 the mouth was an alga which he called Leptothrix biiccalis. 



Klencke, continuing the researches of Biihlmann and Ficinus, 

 drew the dental animalcules, the filaments of Biihlmann (repro- 

 duced in Fig. II of M.) ; and, following the opinions of Ficinus, 

 he even drew the mouths on their ventral side, as can be seen in 

 the quoted figure. 



Meanwhile, the ideas of Robin were accepted, and Leptothrix 

 was generally held to be an alga or fungus siii ge?ieris, excepting 

 by Frey, who, together with Hallier, thought it to be a form of 

 Penicillium glaucum^ and by Tilbury-Fox, who restricted it indis- 

 criminately to a form of Oidium.''' 



After these historical hints. Miller goes on to describe his 

 methods of investigations, from which it appears that the author 

 and the preceding investigators have not acted with that neces- 

 sary care and discernment, which has been demonstrated, in 

 collecting and preparing the contents of the mouth ; nor have they 

 instituted comparisons with the sputa. They directed their best 

 attention to the culture of the microbes of the mouth and to the 

 study of the patina dentaria. They did not avail themselves of 

 the immersion methods except in the special examination of 

 certain fragments or isolated microbes and of their cultures. It is 

 no wonder, therefore, that they should not have met with the fruc- 

 tifications and the productions of Leptothrix by points. 



Miller speaks of cultures on agar or on calf's blood serum, and 

 from thousands of specimens he gives the preference to agar pep- 

 tonised with broth, with an additional 0*5 — i per 100 of sugar. 



The cultures were made from saliva, the tartar of decayed 

 teeth, or scrapings from the surface of the tongue or from dental 

 ulcerations and altered pulps of teeth. The cultures from saliva 

 in the gelatine were negative. Often the bacteria reared in agar 

 did not succeed in gelatine, owing to the low temperature main- 

 tained. 



For a general study, he considers an amplification of 20 to 

 300 diameters sufficient, but for the special morphology he used 

 a homogeneous immersion lens. He speaks of fungi derived from 



* Frey, Bibliography. Tilbury-Fox, by Beale, Work, p. 491. 



