A SIMPLE COOLER FOR USE WITH THE MICROTOME. 



CASWELL GRAVE AND OTTO C. GLASER. 



The microtomist's ability to prepare thin paraffin sections, 

 depends, among other things, on the hardness of his imbedding 

 medium, and this, in turn, on the temperature of the laboratory. 

 Usually this circumstance offers no insurmountable difficulties, 

 but there are times and places when this is not true. To meet 

 such conditions several devices have been suggested and used 

 by various investigators, but we know of none so simple, or as 

 little likely to make difficulties, as the one about to be described. 



The apparatus, which is shown, set up for action, in Fig. i, is 

 essentially a hollow truncated pyramid, open at both ends, and 

 suspended in an inverted position from a standard, so adjusted 

 that the lower end of the shoot is at a convenient distance above 

 the knife. At [the upper end of the inverted pyramid, and 

 surrounded by it, is a tray whose dimensions are less than those 

 of the base of the shoot. This tray is filled with crushed ice, 

 and from one corner of it a drain leads the water to the escape 

 from the lower end of the air-channel. At that point a rubber 

 tube connects the pipe with a suitable receptacle. 



The cooler is easily set up, interferes in nowise with the opera- 

 tor, and is thoroughly effective. When the air of the room 

 strikes the melting ice in the tray, it is chilled and immediately 

 falls between the tray and the walls of the pyramid. In this 

 way a constant stream of cold air pours from the lower end of the 

 shoot, and as this may be placed directly above the paraffin-block 

 and knife-edge, both of these are cooled, and make it possible 

 to cut sections very much thinner than the unmodified temper- 

 ature of the room would allow. 



The extent to which it is desirable to cool the paratim and 

 knife varies with each specific case, but the cooler is adjustable 

 in at least two ways. In the first place the distance of the block 

 from the end of the shoot can be changed within comparatively 



wide limits; in the second place the temperature of the air de- 



240 



