106 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



may then be transferred to celloidin, though it may be necessary to pass 

 certain material through alcohol-ether for 15 minutes. The pieces 

 remain in a thin celloidin solution for 4-5 hours, at 37°-40°. They are 

 then transferred to a thicker solution for 2-3 hours, after which they 

 are placed in thick celloidin. In the last condition they are submitted 

 to the action of chloroform vapour in a closed vessel. In about 

 14 hours they will be of the consistence of cartilage. The blocks are 

 next further hardened in alcohol for some hours. 



Using a Lathe as a Microtome.* — Having a few micro-sections to 

 cut, and being in possession of a small lathe, W. Gribben made the 

 fixture shown in figs. 16 and 17, which enabled him to hold in the slide- 

 rest the razor. By locking the lathe-spindle, to prevent its rotation, the 



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*c* 



Fig. 17. 



object to be cut could be held in a chuck, while the cross-slide of the 

 rest was used to give the cut, and the longitudinal slide to give the feed. 

 Both screws of the slide-rest were provided with micrometers reading to 

 * 001 in., but the cross-slide screw was removed during the cutting to 

 give a more rapid cut. 



The fixture, shown in figs. 16 and 17, is made of two steel bars, 

 A and B, riveted together, and the two pieces of J-in. sheet-brass, 

 and D, which have each a cavity cut out to admit the razor-blade, as 

 shown in section in fig. 17. The flat steel bars E and F are screwed 

 fast to C and D, and the flat side of the razor-blade is held firmly 

 against E and F, by the two capstan-head screws G and H bearing on 

 the concave side of the blade. C and D are held on the round part of B 

 by the two pinching screws K and L, and by loosening these screws, 

 C and D may be swivelled around B, as a centre to alter the clearance 

 angle of the razor. C is graduated into spaces of 5° from 0°-30°, the 

 graduations being read by means of the straight line M scratched on B. 



* Optical Instrument Monthly, i. (1905) pp. 13-14 (3 figs.). 



