124 BACTERIOLOGY. 



middle, half an inch in diameter, and is fastened to an ordinary 

 slide with sealing-wax. The drop to be examined is placed on a 

 large-sized cover-glass and covered with a smaller one. Olive oil 

 or vaseline is painted round the edge of the smaller cover-glass to 

 prevent evaporation, and the preparation is placed over the aperture 

 in the plate. 



The slide bearing the copper plate is clamped to the stage of 



FIG. 52. ISRAEL'S WARMING APPARATUS IN OPERATION. 



the microscope. The flame of a spirit-lamp is applied to the 

 extremity of the rod, and the heat is conducted to the plate and 

 thence transmitted to the specimen. In order that the temperature 

 of the copper plate may be approximately that of the body, the lamp 

 is so adjusted that a fragment of cacao butter and wax, placed close 

 to the preparation, is melted. 



Israel's Warming Apparatus. It is obvious that in employing 

 very high powers a difficulty will be presented by the warm stages 



