Practical bacteriology, microbiology and serum therapy (medical and veterinary) : a text book for laboratory use / by A. Besson ; translated and adapted from the fifth French edition by H.J. Hutchens.

  • Besson, Albert, 1868-
Date:
1913
Catalogue details

Licence: In copyright

Credit: Practical bacteriology, microbiology and serum therapy (medical and veterinary) : a text book for laboratory use / by A. Besson ; translated and adapted from the fifth French edition by H.J. Hutchens. Source: Wellcome Collection.

    898/928 (page 866)
    When the desired volume of air has been aspirated the powdered sodium sulphate is dissolved in a known volume of broth and plates are sown with measured quantities of the liquid. As a control the asbestos plug is trans- ferred with sterile forceps to a tube of broth and this of course should remain sterile. III. Andrewes’ method.—The filtering medium consists of a mixture of glass wool (3-4 parts) and cane sugar (1 part). A straight piece of glass-tubing is used without any constriction and the medium rammed in fairly tightly. After plugging the ends with wool the apparatus is steril- ized at 120° C. and after aspirating the air through it the mixture is pushed out with a sterile glass rod into a plate of melted sterile gelatin.’, B. Methods based upon bubbling the air through liquids. I. Method of Straus and Wurtz.—The apjiaratus consists of a glass cylinder with an appendix at its lower end filled with 10 c.c. of liquefied gelatin the surface of which is covered with a few drops of oil. The upper part of the cylinder is furnished (1) with a lateral tubulure plugged with wool and (2) with a central ground glass opening which is hermetically closed with a glass tube—reaching below to the bottom' of the gelatin in the appendage and above projecting beyond the cylinder —which is plugged with wool. The apparatus is sterilized in the autoclave. When required for use, the lower part of the cylinder is placed in water at about 40° C. to liquefy the gelatin, the lateral tubulure is attached to an aspirator and the wool plug removed. The as- pirated air passes through the central tube B and bubbles through the gelatin in which it deposits the organisms sus- pended in it. (The layer of oil prevents the gelatin frothing.) When 10 litres of air have been aspirated the aspirator is disconnected, and air is gently blown in through the lateral tubulure, thus driving the gelatin up into the central tube. This operation is repeated several times in order to thoroughly wash the tube. Finally, plates are poured with the gelatin. [The apparatus can be used for the simple enumeration of organisms, the gelatin in this case being run over the sides of the cylinder after the fashion of an Esmarch’s roll tube.] Fig. 414.—Straus and Wurtz’ apparatus. This apparatus is very convenient but many organisms are arrested in the delivery tube which is very long and has an irregular surface, so that the results are not very accurate; moreover the apparatus is only available for small volumes of air. II. Miqnel's method.—The apparatus consists of a Pasteur flask with two lateral tubulures attached to opposite sides of its upper part and with a central tube dipping to the bottom. A ground glass cap closes the central tube : one of the lateral tubulures is plugged with wool and the other, used