1895] MICROSCOPICAL JOURNAL 339 



formed, repeat ; if it makes a spot by rapid diffusion, 

 tlie preparation is a success. In tliis case inject the 

 blood vessels with carmine gelatine, harden with bichro- 

 mate, alcohol, gum ; section perpendicularly to the sur- 

 face ; mount in balsam. 



Sioeat glaiids. — Take a piece of skin, as fresh as possi- 

 ble from the fingers, axilla, etc. . . . To fix, use alcohol, 

 or bichromate, or osmic acid, following the proper methods 

 for the reagent selected. Make thickish sections to show 

 the tube, exceedingly thin ones to study the details. 

 Stain with picro-carmine, alum carmine, or h.ipmatoxylin 

 and eosine. 



Sebaceous glands. — Take a piece of the skin of the scro- 

 tum, treat for 10 days with 2 per cent bichromate so- 

 lution. Harden in gum and alcohol. Stain some sections 

 by hsematoxylin and eosine, mount in balsam ; place 

 others in a small tube containing picro-carmine. When 

 properly stained (in about 24 hours), wash in water, ex- 

 pose to the vapor of osmic acid, mount in glycerine. 



Hairs; epidermis. — Put a hair in water containing some 

 40 per cent solution of caustic potash. Raise the tem- 

 perature slightly, scrape the surface with a scalpel, ex- 

 amine the result in a drop of the potash solution. 



Cortical layer. — Put a hair on a slide in a drop of ordi- 

 nary sulphuric acid. Cover and warm gently over a 

 flame. To dissociate the cortical cells press the cover 

 with a needle. 



The medulla. — To study the medullary cells, take white 

 hairs. Boil in a 40 per cent solution of caustic soda 

 until the cells swell up and shrivel. Cover and examine 

 with high power. If the cortical layer prevents obser- 

 vation, tease the hairs with needles. Entire series of 

 medullary elements may thus be readily isolated. 



Sections. — .... To a slide fasten a hair by 

 one end with a drop of wax; repeat with a second hair, 

 ft third, a fourth, etc, side by side, softening the wax 



