The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis.

  • Curtis, Henry J.
Date:
1900
Catalogue details

Licence: In copyright

Credit: The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis. 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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    APPENDIX B Methods for Fixing, Hardening, and Imbedding Tissues Fixation-Prior to hardening the tissues, a fixative is often desirable, a satm-ated sohxtion of Corrosive Sublimate being the best for general use. ^^'Hermann's^tollxtion, for cancer parasite work, is also mentioned on the ''poK^s'olution is also excellent, and is made by satm-ating MuUer's fluid with corrosive subUmate. How to harden fresh tissues: _ i Formalin method.Small pieces of tissue, not more than ^ m. m thickness, are placed in a 1 in 4 solution of formalin for fifteen to twenty hours, and then soaked in a solution of gum mucilage, made from gum arabic, for three or four hours. Sections are cut with a freezing microtome and gently brushed off the razor, or planing iron, into distiUed water. [More rapid sections, sufficiently satisfactory for diagnosis, can be obtained, in an emergency, by hardening thin pieces in pure formalm (a 40 per cent, solution of formic aldehyde) for half an hour, and then soaking in gum for another half-hour.] For the methods of staining, see p. 97 et seq. ii. Alcohol method.—To harden the fresh tissue, a small piece is placed for twenty-four hours in each of the following solutions of alcohol:— 30 per cent., 60 per cent., 90 per cent., and finally in absolute alcohol. It is then ready for imbedding in paraffin or celloidin, as directed below. If the freezing microtome is to be used, the tissue need only be passed through 30 per cent., and 60 per cent., of alcohol, and then methylated spirit, avoiding the use of absolute alcohol. Before letting into gum, however, the tissue must be transferred from the alcohol into water, and allowed to soak for an hour or so, to remove the excess of alcohol. This is not necessary when formalin is used. How to imbed hardened tissues.—A. To imbed in paraffin : 1. From absolute alcohol, transfer to a mixture of equal parts of absolute alcohol and chloroform, till the tissue sinks. 2. Transfer to chloroform for one hour. T