Practical pathology : a manual for students and practitioners / by G. Sims Woodhead.

  • Woodhead, German Sims, Sir, 1855-1921.
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Practical pathology : a manual for students and practitioners / by G. Sims Woodhead. 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.

    69/508 page 49
    THE FREEZING MICROTOME. soaking in the solution for an indefinite length of time, and at the end will cut perfectly, if it has been properly hardened in the first in- stance. The microtome is cooled down to such a point that a drop of gum (B. P. solution) placed on the die or disc (to be afterwards described) is frozen. The tissue which has been soaking in the gum and syrup is taken out with a pair of forceps, gently dried in the folds of a soft cloth, put to soak for a few minutes in gum, and then adjusted as required on the surface of the frozen gum; more gum is painted on the disc around the piece of tissue, to keep it in position,' and to form with it a soHd firm mass, which may be cut in a single section. The mass is frozen just so hard that it will cut like a piece of cheese ; when softer than this, it is not sufiiciently frozen, and when harder, it is very difficult to cut, especially if the sections are of considerable size. The Freezing Microtome. 68. There are several very convenient forms, but it will be necessary here to describe three only—two for freezing with ice, and one for ether freezing. For an instrument which is ready for use at a moment's notice, Cathcart's ether microtome appears to be un- doubtedly the best, and from the student's point of view, it has several very great advantages. It is portable, very clean to work with, its initial cost is moderate, and it can be very inexpensively worked. It is based on a hardwood frame, which may by means of a clamp be firmly fixed to the table; screwed to this is a hollow cylinder, on the top of which is a roughened zinc plate. On each side of the zinc plate is a strip of glass cemented to the wooden frame. By means of a fine-threaded screw, the hollow cylinder, and with it the zinc plate, is raised or lowered at will, through a distance of a quarter of an inch. A double tube is introduced into the hollow cylinder, through one part of which air is driven by a small indiarubber ball arrangement. This stream of air rushing over the mouth of the other part of the tube (which is connected with a bottle of ether) creates a vacuum, and ether is drawn through a small hole; the stream of air completely vaporizes the ether in the chamber under tlic zinc ])late, the temperature of the plate is very rapidly reduced, and the piece of tissue, fixed on with gum (§ 67), is frozen, n
    digitised image 1
    digitised image 2
    digitised image 3