152 



THE ART OF MAKING MICROSCOPE SLIDES 



T.S. Lily bud 



it appears to be deeplj^ stained. This will 

 take not less than three or four hours. The 

 next morning, if staining has taken place 

 overnight, each section is transferred sep- 

 arately to acid alcohol and examined un- 

 der a low power of the microscope until 

 the safranin is observed to be almost re- 

 moved from the cell walls. The sections 

 are then transferred to distilled water, 

 preferably through two changes, to re- 

 move the acid. As soon as the acid has 

 been removed, they are placed in the di- 

 luted Delafield's hematoxylin and left 

 there until the cell walls are deeply 

 stained. This will take from five minutes 

 to half an hour, depending on both the 

 thickness of the section and on the nature 

 of the specimen. The sections are then re- 

 moved, one at a time, to acid alcohol, and 

 left there until the stain has been removed 

 from the celloidin matrix but not from the 

 cell walls. As soon as this result has been 

 achieved the sections are transferred to 

 70% alcohol, in which the\" are rinsed in 

 several changes to remove the acid. 



Now collect as many slides as are re- 

 quired, a mixture of equal parts absolute 

 alcohol and anhydrous chloroform, and 



a bottle of whatever resinous medium has 

 been selected as the mountant. The sec- 

 tions are transferred from 70 % alcohol di- 

 rect to absolute alcohol and chloroform, in 

 which they are allowed to remain until 

 dehydrated. Each section is then passed 

 to cedar oil where it remains until it is 

 clear. The sections are now taken one at a 

 time and drained by the corner against a 

 piece of filter paper. A drop of the resinous 

 medium is placed on the slide, the section 

 placed on this, another drop placed on top, 

 and a coverslip applied. If the sections 

 curl to a slight extent, this may be over- 

 come, as has already been pointed out, by 

 placing either a weight or a clip on the 

 cover. If, however, the sections are badly 

 curled, it is desirable to soften the celloi- 

 din somewhat. This may be done by using 

 a mixture of cedar oil and clove oil (cel- 

 loidin is readily soluble in the latter) in 

 place of the pure cedar oil for the clearing. 

 It is as well to try 10% clove oil in cedar 

 oil at first and, if this does not render the 

 sections flexible enough, to increase the 

 quantity of clove oil until they can be 

 flattened. 



