The micro-organisms of the human mouth : The local and general diseases which are caused by them.

  • Miller, Willoughby Dayton, 1854-1907.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: The micro-organisms of the human mouth : The local and general diseases which are caused by them. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    when one-tenth per cent, sugar was present; if the amount of sugar was increased, the reaction became acid; if it was dimin- islied, the reaction became alkaline. It is equally difficult, I think, to draw a sharp line between putrefactive and fermentative organisms, since many ferment- organisms are capable of decomposing albuminous substances with development of putrefactive products, wdiile on the other hand many organisms which pass as putrefactive, wdien brought into saccharine solutions, give rise to fermentation without the production of a trace of the characteristic products of putrefac- tion. One of the mouth-bacteria which I examined in reference to this question readily dissolved coagulated albumen with devel- opment of bad-smelling gases, among Avhieh SHj (sulphuretted hydrogen) and jSTHj (ammonia) could be easily detected. It also showed an inverting action, in that it converted cane-sugar into dextrose and levulose. In the third place it split ferment- able sugars into lactic acid, with production of CO2 (carbon dioxide). In the fourth place it gave rise to an acid reaction in a solution of starch, while at the same time the solution acquired the capacity of reducing the oxide of copper; in other words, this bacterium showed also a diastatic action. In these different fermentations there undoubtedly arise in the later stages various secondary products, so that the changes which may be brouglit about by this one micro-organism and the products developed under its action make up a very large number. This result affords an explanation of the fact that in an open decomposing substance so many different products may appear, and renders very doubtful the supposition that for every new product in the process of decomposition a new organism must be present. The twenty to thirty different compounds which may be produced in an open decomposing solution are in all probability not produced by one bacterium alone. It is, how- ever, not in accordance with the facts to assume that for every product, or indeed for every stage in the process, a new bac- terium must be introduced. Of the bacteria under consideration I would like to call atten- tion to tive which regularly form large gas-bubbles in the gela- tine or tear it in pieces, as represented in Fig. 8. One of these,