The micro-organisms of fermentation practically considered / by Alfred Jörgensen.

  • Jörgensen, Alfred, 1848-1925.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: The micro-organisms of fermentation practically considered / by Alfred Jörgensen. Source: Wellcome Collection.

    32/198 (page 10)
    In researches in tlie laboratory, where the point in question is also the growth of cultures of organisms concerned in fermentation, much greater demands can be satisfied than in experiments on a practical scale. Here the requirements demand that \ve work with absolutely pure cultures, partly in small quantities, partly in such large masses that they may be interrupted at a given point in the course of the experiment in Order to be transferred to the manufacturing process. Such conditions, which are wanting in the technical appli- cation, are sought to be realized in the laboratory, which is specially arranged for these investigations; and we will now briefly sketch these conditions, and the manner and form in which they are fulfilled. We will on purely historical grounds hegin with the last memhers—the vessels and liquids, which receive the originally prepared small pure-cultures—and the expedients which are employed in the cultivation. It is necessary that, before the introduction of the inoculating substance, these fiasks and hquids should be sterile, i.e., free from all living, active germs, and also that the surrounding apparatus and the air of the place in which the work is performed should contain as few hving germs as possible. The same remark applies naturally to the clothing and hands of the. experimenter. The requisite sterilization and disinfection, which, of com’se, should also be striven for technically, is naturally of quite a different natm’e to Chemical purity. It can and must be carried out in a different manner. The pieces of apparatus, the nature of which will admit of the application of a temperature considerably above the boihng-point (for example, heating at 150° C. for two hoius), can be directly sterilized in this way; metallic objects, as forceps, tongs, &c., and also glass apparatus can be quickly sterilized by ignition or by strong heating with a flame, and subsequent cooling in a germ-free space. Apparatus of inflammable material, when it has previously been mechanically pmüfied, may be sterilized on the surface by being repeatedly and quickly passed through a flame. Nutritive liquids are brought to a state of sterility by boiling in the ordmary way for a length of time which