842 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



voir (Gudden), or standing free on the table (Schiefferdecker), it is 

 attached to the table, and by this means both hands are set free. 

 Compared with Gudden's microtome, there is a gain in the increased 

 convenience and the reduced loss of light ; while there is in- 



FiG. 196. Fig. 197. 



creased stability and firmness, compared with Schiefferdecker's 

 method of simply placing the instrument on the table. 



" It may be objected that cutting under water is impracticable 

 with this instrument. To this it may be replied that section cutting 

 under water is only intended to obviate the brittleness of the prepa- 

 ration ; the same object is attained by glycerine jelly in a far more 

 practical manner. This imparts to the whole a uniform consistency 

 for cutting purposes, and binds it together into one firm mass 

 without a trace of brittleness. Cutting under water can therefore be 

 dispensed with. 



"Katsch, of Munich, has made an arrangement for the larger 

 instruments, by which a large wheel with four projecting teeth — 

 placed horizontally and soldered to the lower head of the micrometer 

 gcrew — allows the bottom of the cylinder to be raised or depressed 

 more quickly. Eainer, of Vienna, has made the whole bottom of the 

 cylinder, together with the micrometer screw, to fit in with a kind of 

 bayonet fixing, so that a rapid change of the object (imbedded in oil 

 and wax) is practicable. The fixing of the wax and oil cylinder 

 enclosing the object is effected in the older instruments on Gudden's 

 plan by means of three small buttons, the section of which is mush- 

 room-shaped, which project from the movable base-plate of the 

 microtome. Latterly Tliamm, of Berlin, has substituted for these 

 buttons a long gi'oove, 1 cm. broad and 1 mm. deep, which runs across 

 the middle of the base-plate of the cylinder ; by this means facility 

 in taking out the oil and wax cylinder is attained." 



Knife for Large Sections. — Dr. Loewe also explains that for large 

 sections through the bodies of mature animals a very long, heavy, 

 and broad knife should be used, as in Fig. 198, which also gives a 

 transverse section showing the peculiar grinding away of the blade to 



