244 SUMMARY OF CUEKENT RESEARCHES RELATING TO 



The paraffin imbedding was carried out in the same vessel as the fixa- 

 tion, etc., in order not to lose any of the eggs, and also to insure the 

 material being on the surface of the block. For the larvge similar 

 methods were adopted. Picro-carmin was found to give better results^ 

 than Delafield's h^ematoxylin when the material was stained e7i masse. 

 Creosote was used immediately after the acid-alcohol stage in order 

 to prevent accidei^ttil loss of the minutest larvie. For the camera 

 drawings of the preparations, black copying paper and finely pointed 

 white pencils were used. 



(3) Cutting-, including' Imbedding- and Microtomes. 



Method of Cutting Frozen Sections of Fresh Tissues for Immediate 

 Microscopic Diagnosis of Tumors during Operations.* — C. B. Lock- 

 wood and E. H. Shaw describe the procedure, which may be divided into- 

 two parts, as follows. 



1. The Arranging and Fixing -up of the Apparatus required. — The 

 microtome must be fixed on a firm table, and all the instruments 

 arranged in a convenient manner. A mental survey of the cutting,, 

 mounting, and staining of a section is then made, in order to make 

 sure that everything is present and in its proper place. This insures 

 that no time will ])e wasted when once the process is begun. 



2. Preparation of the Microscopic Section. — {a) The selected piece of 

 tissue received from the surgeon is placed directly on to the brass disk 

 of an ether-freezing microtome, and is surrounded by gum solution, 

 (ft) The tissue and gum are frozen, and sections made by a razor on a 

 carrier, {c) The sections are transferred to a dish of cold water, and, 

 after separating them with a glass rod, a suitable section is lifted out. 

 {d) It is dipped for a moment into pure methylated spirit, and (e) then 

 placed in another larger dish of cold water ; the currents set up by the 

 spirit in the water cause the section to spread out flat. (/) A glass slide 

 is dipped in the water under the section, and the latter is lifted out aS' 

 the slide is slowly drawn up out of the water again, (f/) The water is 

 di'ained off the slide, and a drop or two of stain (Loeffler's methylen- 

 blue) is allowed to fall dh'ectly on to the section, {h) A thin cover-glass 

 is placed on the stain and section after ;-}-5 seconds ; it is lightly pressed 

 down so as to drive out excess of stain ; this is then blotted off, and the 

 specimen is ready for examination under the Microscope. 



New Form of Microtome-knife.j — E. G. Martin recommends 

 especially for class purposes, the following instrument (fig. 47). Use 

 is made of the safety razor-blades, and the form for which this instru- 

 ment is adapted is the one which first appeared on the market. The 

 device consists essentially of a stout blade split lengthwise in a plane 

 passing through the cutting edge, and having two parts hinged together 

 at the side away from the cutting edge. 



By means of a set-screw the two parts of the blade may be firmly 

 pressed together and held so. The thin blade which is to be used in the 

 actual cutting edge is placed in position between the two parts of tha 



* Brit. Med. Journ., 1907, i. pp. 127-9. 



t Proc. Indiana Acad. Sci. for 1905 (1906) pp. 203-4 (1 fig.).. 



