6 2 THE AMERICAN MONTHLY [Feb 



the tip of the finger, projecting- as it does above the sur- 

 face, admits of an ordinary mounted needle being- drawn 

 quickly across its surface. The needle is then, with a cir- 

 cular motion, swept over the surface of a cover-glass held 

 between the thumb and finger of the left hand. With a 

 little practice, this method gives very satisfactory results, 

 quite an even spread, and the corpucles are very little dis- 

 torted. Necessarily in blood measurements, this latter is 

 of the utmost importance. — Harold N. Moyer. 



Drilling Lenses. — Make a lubricant with 1-2 drachm 

 aqua ammonia, 1 1-2 drachm sulphuric ether, 1-2 oz. g-um 

 camphor, 1 oz. spirits turpentine. Keep it corked and in 

 a low glass stopped bottle. The drill must be of steel as 

 hard as file steel 2 1-2 m, m, in dia. by 4 cm. long. Fit it 

 in a handle of rubber with loose cap screw. Grind an oval 

 head entirely around the piece of steel, heat it red and 

 plunge in cold water, grind the head on two sides flat but 

 without drawing the temper at all. Stroke on an oil-stone 

 to give a sharp finished point, rotating it while stroking. 

 Hold the lens or glass with the left hand with the point to 

 be drilled on a rounded knob of wood or cork securely 

 anchored. Keep the pariscopic side down. Drill half 

 through and then turn and drill opposite. Hold the screw 

 driver between thumb and second finger. Put the index 

 finger inthe revolving cap. Dip in the lubricating solu- 

 tion as required. The first hole may be enlarged by a 

 round file moistened with the same lubricant. Watch 

 crystals, plate glass, or any other glass may be drilled in 

 like manner. 



MEDICAL MICROSCOPY. 



Inflammation. — In man, itis characterized by four cardi- 

 nal symptoms ; redness,swelling,heat,pain. But in the frog 

 heat is lacking. Virchow held that the essence of inflam- 

 mation was action of tissue cells. Acted upon by some 

 irritation, they began to proliferate or multiply by division, 

 thereby producing new material. 



Cohnheim observed under the microscope what took 



