ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



113 



bar, grooved to fit the guide-flanges. It is raised to the required tem- 

 perature by means of the heater shown in fig. 18. Before -use, the 

 plate is moistened with turpentine. The most convenient temperatures 

 are about 52° C. for the plate, and 100° C. for the roller. 



Fig. 18. 



Manipulation of Paraffin Sections.* — J. T.Wilson hastens the setting 

 of paraffin blocks by using a metal plate on the floor of the embedding 

 chamber, and placing this on a freezing microtome. 



For floating out paraffin sections placed on top of the water-bath he 

 employs a mercury surface as an artificial horizon. On the top of the 

 bath is placed a shallow glass tray filled to a depth of 6 or 7 mm. with 

 mercury. On this surface the slides may be placed until the sections 

 are completely flattened. 



For celloidin-paraffin sections a much deeper tray or box is required ; 

 this is covered with an accurately fitting lid. When the slides are placed 

 on the mercury surface a small pledget of cotton-wool soaked in ether is 

 placed in one corner, and then the lid is put on. 



For passing blocks of tissue through various fluids he uses short seg- 

 ments of wide glass tubing 18 to 30 mm. in diameter ; one end is closed 

 with mosquito netting, or some fine material, while the other is plugged 

 with a perforated cork ; the cork must be bulky enough to float the 

 whole in the fluid. 



Tetrander Microtome.! — P. Mayer describes this instrument, which 

 owes its name to the number of persons who co-operated in the design. 



* Zeitschr. wiss. Mikrosk., xxvii. (1910) pp. 232-4. 

 t Tom. cit., pp. 52-62. 



Feb. 15th, 1011 



