CM. VII.} 



ISOLATION OF ELEMENTS. 



155 



S 247. Staining the Cells. — Almost any stain may be used for the 

 formalin dissociated cells. As an example, one may use eosin (§ 305). 

 This may be drawn under the cover of the already mounted preparation 

 (Fig. 128), or a new preparation may be made and the scrapings 

 mixed with a drop of the eosin before putting on the cover-glass. It is 

 an advantage to stud}- unstained preparations, otherwise one ma}' obtain 

 the erroneous opinion that the structure cannot be seen unless it is 

 stained. The stain makes the structural features somewhat plainer ; it 

 also accentuates some features and does not affect so markedly others. 



S 248. Permanent Preparations of Isolated Cells. — If one de- 

 sires to make a permanent preparation of the isolated cells it may be 

 done by placing a drop of glycerin at the edge of the cover and allowing 

 it to diffuse under the cover, or the diffusion may be hurried by using 



Fig. 130. Adjustable lens holder with universal joint. This is especially useful 

 for gross dissections, and for dissecting the partly isolated elements with needles. 



a piece of blotting paper, as shown in Fig. 128. One may also make a 

 new preparation and either with or without staining, mix the cells with 

 a drop of glycerin on the slide and then cover, or one may use glycerin 

 jelly (§ 239, 309). 



£ 249. Isolation of Muscular Fibers. — For this the formal disso- 

 ciator may be used (§ 245, 308), but the nitric acid method is more sue- 



