530 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



tappet a single rotation of the knob may be made to impart to the 

 object an elevation varying from O'OOl to 0*020 mm. Thicker 

 sections than these may be cut by turning the knob more than once. 

 Any kind of knife may be used in conjunction with this microtome. 

 Celloidin preparations are appropriately cut with a knife having a 

 blade 24 cm. long and 33 mm. wide, and a back 13 mm. thick. The 

 various parts of the microtome are either enamelled or nickel-plated. 



Fig. 95. 



Rapid Examination of Tumours for Diagnostic Purposes.* — A. 

 Leitch finds the following method gives # very satisfactory results : — 

 Thin slices of the doubtful tissue, about 1 mm. in thickness, are re- 

 moved, and placed immediately in acetone and taken to the laboratory. 

 The slices are transferred to hot water for a few seconds, dipped in 

 gum solution, and placed on the stage of a freezing-microtome. The 

 current of carbon dioxide is turned on, and the whole tissue is well 

 frozen in less than one minute. The microtome used is a very handy 

 little apparatus made by Leitz, the knife-carrier of which is sufficiently 

 heavy to give a good momentum to the razor. The sections, as they fly 

 off tangentially, are caught in a basin of water held by an assistant. 

 They are floated on to a glass slide, the excess of water is dried off, 

 and a drop of acetone solution of " krystallviolet " is placed on the 

 section. This fixes it to the slide and stains it rapidly. The excess 

 stain is removed with water and acetone, and the section is cleared with 

 xylol, and is then in a condition to be examined under the Microscope. 

 Good histological preparations can thus be obtained and may be kept 

 permanently. Allowing 2 minutes for conveyance of the tissue from 



* Brit. Med. Journ. (1909) i. pp. 1226-7. 



