346 



SUMMARY OP CURRENT RESEARCHES RELATING TO 



wheel G, which is automatic in its action, being moved forward any 

 distance required at each stroke of the knife. This movement is 

 adjusted by a screw at the side, by which the number of teeth moved 

 forward at each stroke is determined. If the instrument is so 

 adjusted that the wheel moves one tooth at each stroke the thickness 

 of the section will be 1/3G00 in., or 7//,, and so on up to 10 teeth or 

 1/360 in. (70 fx). 



The arrangement for ribbon cutting consists of two drums H H 

 carrying the ribbon C. The distance the ribbon moves is regulated 

 by a small ratchet wheel I, capable of minute adjustment and varying 

 according to the breadth of the section cut. 



The ether freezer consists of an indiarubber tube communicating 

 with a chamber E upon the outside of which the object to be frozen is 

 placed ; a hand-bellows K, an intermediate regiilating bladder L, 

 and a bottle M in which the ether is placed, and into which the two 

 tubes for the ether and drainage are fitted. 



The zinc tray N holds any droppings. 



If desired a crank movement can also be applied, whereby a con- 

 tinuous motion is given to the knife carrier and to the ribbon 

 apparatus. 



The advantage is obvious of having a simple microtome to which 

 a simple ribbon apparatus can be attached when it is desired to cut 

 series of sections, and which does not interfere with the ordinary use 

 of the instrument. 



Reichert's Simple Hand-Microtome — Figs. 85 and 86 show the 

 simple hand-microtome of C. Eeichert for objects of 15-25 mm. in 

 diameter. 



A metal cylinder has at the lower end a disk a with an excentric 

 aperture. One end of a lever b within the cylinder passes through 



Fig. 85. 



Fig. 86. 



the aperture, while the other presses against the piece of pith c used 

 for imbedding, and the pressure can be increased or diminished accord- 

 ing as a is rotated. Over the upper end of the cylinder is fitted a 



