292 THE AMERICAN MONTHLY [Sept 



cent alcohol be placed upon it, the section, if curled, will 

 tend to flatten itself when placed on the alcohol. If the 

 slide now be placed in a thermostat for a few hours, at a 

 temperature near the melting point of paraffin, the heat 

 will cause any wrinkles or irregularities of the section to 

 disappear; the alcohol slowly evaporates and when the 

 slide is thoroughly dry the albumen molecules of th^ tis- 

 sue adhere quite firmly to the slide, as noted by Gaule. 

 After this the slide may be heated gently over a flame 

 until the paraffin begins to melt. If any moisture remains 

 the section will be quite likely to loosen during the latter 

 stages. Thick sections do not adhere so firmly as ili.n 

 ones. The slides may then be immersed in a jar of tur- 

 pentine or any solvent of paraffin and carried through 

 the various grades of alcohol to water. 



A shorter method, in which there is as firm adhesion 

 of the section to the slide, is to bring the slide in contact 

 with aniline oil for a few minutes after the treatment with 

 the turpentine, absorbing the superfluous turpentine with 

 filter paper. The aniline oil is also removed by means 

 of filter paper. The section is then thoroughly Avashed in 

 distilled water which removes the oil, and the tissue is 

 then stained and washed in water. If aniline stains are 

 used, a hurried rinsing is sufficient. Drain or absorbe the 

 water and again apply the aniline oil. Besides clearing 

 the section the oil tends to remove the aniline stain and 

 care must be exercised in not letting this process go too 

 far. Displace the aniline oil with xylol and mount in 

 balsam. The color ought not to fade if the aniline oil 

 has been thoroughly removed. 



With certain stains, or combinations of them, the ani- 

 line oil may not succeed in preserving the sharp defini- 

 tion of the color. Under such conditions the section, 

 after staining, may be treated directly with absolute 

 alcohol to dehydrate and remove any superfluous stain. 

 Some aniline dyes are not as soluble in absolute alcohol 



