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night the specimen would be well hardened — and should be transferred to 

 alcohol. The material should be cut into tolerably thin slices in suitable 

 directions, not cutting quite through the lump. The material placed in a 

 piece of net or gauze or antiseptic bandage is then to be hung in a bottle 

 filled with the hardening fluid, so as to keep the material from touching the 

 bottom, or it might be attached to a piece of string with the label hanging 

 outside, thus permitting any refuse to drop to the bottom of the bottle 

 leaviDg the specimen clean. (Specimens were handed round ; some pro- 

 perly, others not properly hardened.) 



The nest step was to place the specimen in preserving fluid. The best 

 fluid for this purpose was spirit of 95°. 



When cutting by hand, or with some of the section cutters, it was neces- 

 sary to embed the specimen in a mixture of equal parts of wax and oil. A 

 small paper boat half filled with this mixture being provided, the specimen 

 (if in alcohol, first getting rid of the spirit by a few minutes' exposure to the 

 air) is to be dipped into the wax and allowed to fall to the bottom ; a drop 

 of wax being first formed to serve as a pedestal, to keep the material from 

 falling quite to the bottom, the end of the boat in which the specimen is 

 placed should be marked, otherwise it might happen when the mistake 

 was discovered nothing would remain to hold the specimen when cutting. 

 Another plan was to use a short tube with a cork at the end, but this was 

 not so certain in its operation. 



Mr. Groves then introduced and described several forms of microtome, 

 one being practically the original Sterling microtome, which he had 

 described to the Club, with Dr. Matthew's improvements. The wooden 

 plug in this machine prevented any rocking or rotation of the wax. The 

 razor best adapted for use with it was one with a straight edge. The 

 blade need not be flat, but it must have a straight edge. The motion in 

 cutting should not be a sliding or pushing cut, but a sort of rotating cut. 

 The direction in which to make the cut was determined by the material 

 which only experience could give. With freezing microtomes it was necessary 

 to get rid of the alcohol. Take a small piece of the material not more than 

 ^inch thick, leave it in water for 24 hours, transfer to gum mucilage with a 

 trace of camphor water (five drops of w y ater to an ounce of gum) to prevent 

 the gum freezing into a hard mass like ice, which would chip the razor. 

 The gum would freeze into the consistency of hard cheese. 



In preparing the mixture of ice and salt the ice must be thoroughly 

 pounded, first with the ice prick, then with a mallet, until it was a perfect 

 powder. This must be thoroughly mixed with an equal quantity of salt. 



Dr. Pritchard's machine was very portable and efficient. To use it the 

 cylinder was placed in a bowl of ice and salt, the specimen being placed on 

 the top of the cylinder with a little gum mucilage and the felt cap put on. 

 When frozen the cap was placed on the other end of the cylinder which then 

 served as a handle. 



In cutting specimens embedded in wax and oil the razor must be kept 

 constantly wet, spirit was preferable for this purpose, and should be placed 



