328 Dr. Beetle's Preparations for the Microscope. 



opening is made in the sternum, the heart exposed, and a fine 

 injecting- pipe, after being filled with a little injection, is tied 

 on the artery. The injection is completed in twenty or thirty 

 minutes, the fluid employed consisting of — 



Price's glycerine 2 oz. by measure. 



Tincture of sesquichloride of iron 10 drops. 



Ferrocyanide of potassium . . 3 grains. 



Strong hydrochloric acid ... 3 drops. 



Water 1 ounce. 



Dr. Beale tells us that, when the injection is complete, the 

 abdominal cavity is to be opened, and the viscera washed with 

 strong glycerine. The mouth is slit on one side, and the 

 pharynx washed in the same way. Any organ may then be 

 dealt with separately, or the whole body, the legs having been 

 removed, may be immersed in a carmine solution, of which the 

 following formula is recommended : — 



Carmine 10 grains. 



Strong liquor ammonia . \ dram. 



Price's glycerine 2 ounces. 



Distilled water 2 „ 



Alcohol 



a ,) 



The carmine is first placed in a test-tube and shaken up 

 with the ammonia, then boiled for a few seconds and allowed 

 to cool. After an hour the other ingredients are added, and 

 the solution filtered. Dr. Beale finds from four to six or eight 

 hours, with occasional motion and gentle pressure, to be 

 necessary to ensure the action of the fluid on every part. The 

 blue colour imparted by the injection disappears when the 

 carmine staining is complete. The frog is then removed from 

 the carmine solution and well washed with common glycerine, 

 after which strong Price's glycerine is poured over it, and in 

 six or twelve hours this is poured off, and enough fresh 

 glycerine (together with three or four drops of strong acetic 

 acid) added to cover the preparation. In this state it is left 

 for some days, and when it is ready for examination, a small 

 piece of some vascular part will show, under the microscope, 

 that the injected vessels arc bright blue and the nuclei of the 

 tissues bright red. 



The particular portions to be examined are covered with 

 glycerine on a slide, slightly pressed, and washed with glyce- 

 rine containing five drops of acetic acid to the ounce. Pro- 

 cesses of this kind are repeated after an interval of some da} r s, 

 and at last, by very graduahand gentle treatment, a portion is 

 reduced to a condition in which the finest muscular or nerve 



