1895 THE MICROSCOPE. 159 



ment and many state experiment stations pay a great deal of 

 attention to the Erj^sippei as they are very destructive to the 

 host of plants on which the}^ quarter themselves. If on the first 

 examination the appendages do not appear, try a new speci- 

 men. Often on transferring a specimen to a slip the appen- 

 dages are broken off or rolled up so that the distinguishing 

 ends cannot be seen. 



White Zinc Cement. — Oxide of zinc rubbed up with equal 

 parts of oil of turpentine and eight parts of solution of gum. 

 Dammar in turpentine of a syrupy consistence, or Canada bal- 

 sam, chloroform and oxide of zinc. 



A clean satisfactory way may be effected by purchasing a 

 tube of white z'nc from a dealer in supplies. Be sure and ob- 

 tain white zinc and nothiufij else; dealers will inform purchasers 

 that flake white or somthing else is just as good. To make a 

 good cdl, express a little of the white zinc on a flat hard sur- 

 face, drop upon it a small amount of pure clear linseed oil; mix 

 wdth a putty knife; when of proper consistence turn rings upon 

 the turn table, using a very fiae pointed painter's pencil. The 

 proper consistence can be gained by experience only. If too 

 thick the rings will not readily turn and if too thin the rings 

 when turned will flow. If made properly, set the slides away 

 until they are hard and dry, then they will be cells that are a 

 comfort to the user. Mix a batch of the zinc whenever you 

 wish to make cells; it does not seem to work well when mixed 

 up and set away for future use. 



Brunswick Black is asphalhem dissolved in turpentine. A 

 little India-rubber dissolved in mineral naptha is sometimes 

 added. 



Preparation by Teasing. — A minute fragment of tissue 

 should be placed in a drop of fluid on a slide, and torn or un- 

 ravelled by two sharp needles. This is accomplished more eas 

 ily after maceration, and sometimes it is necessary to macerate 

 in a substance which will dissolve the connecting material. 

 This picking or teasing should be s'owly and accurately per- 

 formed. Beginners often fail of a good preparation by ceasing 

 too soon, as well as by having too large a specimen. The most 

 delicate manipulation is required to isolate nerve cells and pro- 

 cesses. 



