216 



Specific Examples of Slide Making 





' i ; Ski \ 4 **'£&£ < • *"-' 







149 



150 



Figs. 149 and 150. Details from a thoroughly bad slide made by the method de- 

 scribed in this example. Fig. 149 shows one villus. Notice at 1 the tears caused by a 

 blunt knife and the folds that have resulted from imperfect flattening of the section. 

 Compare 3 and 4 in Fig. 150 with 3 in Fig. 148. This animal had evidently been 

 dead for some time before the section was fixed so that autolysis has destroyed much 

 of the epithelium and so damaged the rest of the tissue that sharp differentiation is 

 not possible. 



may be enclosed in a small fold of cheesecloth for suspension. After 24 ru- 

 in this volume of alcohol, the object will be completely penetrated by the 

 96 per cent alcohol and should be transferred to absolute alcohol, using 

 the same volume in a jar of similar construction. It is useful to place 

 absolute alcohol jar, not only to make sure that the alcohol is absolute 

 about a %-in. layer of anhydrous copper sulfate at the bottom of the 

 but also to indicate, as it changes to blue, when this jar should be re- 

 moved from service. Of the many dealcoholizing (clearing) agents that 

 may be used, the author would select benzene in the present case because 

 it is less liable to harden the circular muscles of the intestine than is 

 xylene. Since benzene is lighter than absolute alcohol, it is not possible 

 to use the hanging technique for clearing, and the object should be placed 

 in about 25 ml of benzene, which should be changed when diffusion cur- 

 rents no longer rise from the object. This is likely to be about 6 hr for an 

 object of the size under discussion, and a second bath of at least 6 hr 

 should be given. 



It is necessary to select the medium in which embedding is to be done. 

 The author would recommend the rubber paraffin of Hance, which must, 



