214 MICROSCOPICAL TECHNIQUE. 



many workers to substitute glycerine jelly wherever practicable. 

 Many formulae have been published for this medium, but one 

 recently published by J. E. Huber possesses a degree of novelty 

 in that he excludes the use of water as one of the ingredients. 

 He recommends that clear gelatine (i drachm) be allowed to 

 macerate in glycerine (ijoz. by weight) overnight, and that the 

 mixture should then be heated in a water-bath until solution is 

 perfect. Specimens to be mounted should be soaked first in 

 dilute, then in stronger glycerine, afterwards placed on a slide with 

 as little dilute glycerine as possible, and covered with hot jelly. 

 After cooling, the cover-glass is placed over the object, heat applied 

 to the slide, and the cover pressed down into position when the 

 jelly melts. On cooHng overnight the slide may be cleaned and 

 finished off. The mounts are stated to be free from the liability 

 to shrinkage that often occurs when glycerine jelly is used. 



Notes on Bone Technique.— In the section " Microscopy " in 

 the American N'aturalist for June, 1892, Dr. C. O. Whitman gives 

 the following notes for preparing sections of bone : — " In prepar- 

 ing bones for sectioning, it is w^ell to have fresh material taken from 

 a young individual. After the soft parts are removed, the bone is 

 cut into short pieces, and then macerated in water until the 

 medulla is easily washed out. They are then ready to section. 



Preparations nearly as good as those obtained by maceration 

 may be made from fresh tissue. Thin sections are cut from the 

 desired region with a fine saw. From these the medulla should 

 be carefully washed out under a jet of water ; they are then 

 ground until the desired thinness is reached, again washed, dried, 

 and mounted. The grinding may be done with a file or on a 

 revolving grindstone, or with emery on a dentist's lathe,* or 

 between pieces of compact pumice stone, followed by hones of 

 finer grain, and finally polished on a piece of smooth leather or 

 buckskin, covered with powdered chalk. 



Another method is to grind the bone on a glass plate with 

 emery of different degrees of fineness. This may be accomplished 

 by pressing the section down with the fingers, or it may be fas- 

 tened to a cork by means of sealing-wax or thick balsam. It is 

 then polished on one side until smooth ; then the wax of balsam 



* Healey, Anier. Mon. Mic7'o. Journ., 1884. 



