182 Specific Examples of Slide Making 



Naturally they sink through it, coming to rest on the surface of the layer of 

 terpineol into which they sink slowly without any strong diffusion cur- 

 rents. They will be seen to have sunk to the bottom after a little while, 

 but there will still be a quantity of alcohol diffusing upward from them. 

 As soon as these diffusion currents have ceased, the alcohol should be 

 drawn from the top of the tube with a pipette and the specimens trans- 

 ferred to clean terpineol. When they are in fresh terpineol, they should 

 be examined carefully under a microscope to make sure that they are 

 glass-clear without the least trace of milkiness. If they appear slightly 

 milky, they have either been dehydrated insufficiently or the alcohol used 

 for the preparation has become contaminated with water. In either case 

 before being transferred to a tube of fresh alcohol for complete dehy- 

 dration they must be transferred back into terpineol in the manner de- 

 scribed. It is a sheer waste of time to endeavor to prepare a balsam 

 mount from a specimen that is not perfectly transparent in the clearing 

 medium. 



When all the specimens are in natural balsam, have ready some clean 

 slides, some clean %-in. circular coverslips, and a balsam bottle contain- 

 ing natural balsam. The author's preference for the natural balsam rather 

 than a solution of this material in some solvent has been explained pre- 

 viously. For example, a drop of the natural balsam is placed on each of 

 six slides, and then, one at a time, six specimens are lifted from the 

 terpineol and placed on top of the balsam. The specimens will sink 

 through the balsam very slowly, so that these six slides should be pushed 

 aside while the next six slides have drops of balsam put on them, and so 

 on. As soon as a specimen has sunk to the bottom of the drop of balsam, 

 a coverslip is held horizontally above, touched to the top of the drop, 

 and then pushed down with a needle until the specimen is flattened 

 firmly against the slide. Since these specimens have been properly hard- 

 ened and flattened, there is no risk of their being damaged by drying the 

 mount under pressure, so a clip can be applied (see Fig. 83) and the 

 slides placed on a warm table to harden. Each is cleaned, finished, and 

 labeled in the manner suggested previously. 



SUMMARY 



1. Narcotize with menthol. 



2. Kill with 4% formaldehyde. 



3. Harden selected polyps compressed between slides in 95% alcohol. 



4. Stain 1 to 24 hr in Grenadier's alcoholic borax carmine. 



5. Differentiate in acid 70% alcohol until pink. 



6. Dehydrate, clear in terpineol, and mount in balsam. 



