58 THE MICROSCOPE. [April, 



PREPARING DRUGS FOR EXAMINATION. 

 By A. F. Rogers. 



Fresh vegetable tissues often cannot be sectioned without pre- 

 viously being hardened. But this may be accomplished by soak- 

 ing them for 7 to 10 days in pure methylated spirit. This should 

 be changed every day and until all color has ceased to appear. 

 Preserve in alcohol until the tissues are wanted for sectioning. 



But frequently drugs are dry and very hard ; they must then 

 be softened by soaking in water with a little methylated spirit, 

 or even soaking in hot water. Sometimes a three per cent, so- 

 lution of potassa can be safely used — that is. in cases in which 

 the cell contents, being injured, unfit the section for examina- 

 tion. 



To make sections of soft stems, ovaries, etc., by hand, take the 

 specimen between the thumb and forefinger of the left hand, hold 

 the finger horizontally so that its upper surface may form a table 

 on which the blade of a razor may slide, keep the handle of the 

 razor in a line with the blade, and draw it from heel to tip through 

 the specimen and towards yourself; keep the blade w r ell wet 

 with very dilute alcohol, and float off the sections as they are cut 

 into a saucer of water. 



The drug is, however, frequently too hard for section-cutting 

 bv hand ; it is then necessary to use a microtome. The Army 

 Medical Museum pattern is more frequently used in this country. 

 This is simply a brass well, into which fits a very finely cut 

 screw. The instrument having been firmly fixed to a table by 

 means of a clamp screw, the specimem is imbedded in a piece of 

 carrot, or in a mixture of lard and hard paraffin ; the whole is 

 put into the well, and, as the screw is turned and gradually 

 pushes out the whole of the contents of the well, sections are 

 made with a razor or section knife. This is nothing more than a 

 large razor without a handle. The knife and specimen should 

 be kept well wet with dilute alcohol, and the sections may be 

 kept until wanted in slightly diluted spirit. 



It is not necessarv to use rectified spirit in section preparing, 

 but the methylated spirit must not contain any kind of gum. A 

 rough-and-readv test of the fitness of the spirit is to pour it into 

 water ; it should not affect the brilliancy of the water in the 

 slightest degree. For very friable tissues a special treatment is 

 required. First, soak the drug in strong alcohol, then in ether. 

 Now prepare a solution of celloidin in equal parts of alcohol and 

 ether, about the thickness of glycerin (reserve one-third of 

 this solution). To one-third of this solution add its own bulk 

 of alcohol and ether in equal parts, and to the remaining one- 



