138 



Modern Microscopy 



wool or a piece of felt on the bottom of the steamer, to pro- 

 tect the test-tubes from breakage ; half fill with water, add 

 a thermometer, ligh't the lamp, and on the desired tem- 

 perature being attained, put some paraffin in the test-tubes, 

 place them in the steamer, and when the paraffin has 

 melted add the specimens. 



After use dry the apparatus so that rust may not set in. 

 If this is attended to it will last for years. 



When a proper embedding bath cannot be obtained, 



FIG. 51. POTATO-STEAMER CONVERTED INTO AN EMBEDDING BATH. 



A, Thermometer ; B, Test-tubes ; C, Disc of tin ; D, Tin supports ; E, Water ; 

 F, Cotton-wool ; G, Spirit or small paraffin lamp. 



tissues may be infiltrated with paraffin in the following way : 

 Dehydrate the specimen in absolute alcohol ; then place in 

 a quantity of chloroform or benzole, ten or twelve times the 

 bulk of the tissue, until saturated ; add small pieces of 

 paraffin until no more will dissolve, and set aside for 

 several hours. Apply gentle heat to drive off the solvent 

 and melt the paraffin, after which the tissue can be re- 

 moved and embedded in a pill-box of paraffin of the desired 

 melting-point. 



