366 . METHODS. 



tion. As soon as the paraffin has set, chill it rapidly with cold water, otherwise 

 the paraffin is likely to crystallize and therefore to cut badly. 

 B, To ImhedinCelloidin: 



1. Dehydrate the mass thoroughly in 95 per cent, alcohol, four to twenty- 

 four hours. 



2. Place mass for twenty-four hours in alcohol and ether, equal parts. 



3. Place mass in thin syrupy solution of celloidin in equal parts of ether and 

 alcohol for twenty-four hours. 



4. Place mass in thick viscid solution of celloidin in equal parts of ether and 

 alcohol for twenty-four hours. 



5. Set mass on block of vulcanite, compressed fiber, or maple- wood, and as 

 soon as a film has formed over the surface of the celloidin (two to five minutes) — 



6. Immerse in 80 per cent, alcohol for twenty-four hours. 



7. Cut. 



Method of Mounting Paraffin Sections. 



The student is advised to use slides 40 x 76 mm. and from 1.75 to 2 mm. 

 thick. The thick slides are much better than the thin ones recommended by 

 dealers. The cover-glasses ought to be 35 x 50 mm. and o. 1 7 to o. 18 mm. ; they 

 may be readily obtained from German makers, but are difficult to secure from 

 American manufacturers except at an exorbitant price. 



The serial order of the sections should be preserved with the utmost care, 

 and time spent in arranging the sections in straight rows will be found to be time 

 saved. 



The albumen-glycerin methods of fastening the sections to the slide will be 

 found satisfactory. 



Formula : Take the white of one fresh egg, beat slightly until equally fluid, filter it (it will take about 

 twenty-four hours) and add an equal amount of glycerin. To this fluid add a small piece of camphor. 



1. Clean the slide thoroughly. 



2. Put on a small drop of albumen solution. 



3. Spread it out very thin with the finger. 



4. Add five or six drops of distilled water, which must flow evenly over the 

 coating of albumen. 



5. Place the sections on slide in regular rows. 



6. Warm the slides gently over an alcohol flame, to allow the sections to 

 flatten. The paraffin must not melt. 



7. Place the slides in oven for twelve to twenty-four hours to evaporate 

 the water completely. 



