CELESTIN BLUE B-EOSIN-STAINED INTESTINE 113 



As soon as the knife is seen to be approaching the object and the block in its 

 entirety is being cut, the ribbon must be observed most carefully to see that it 

 is suffering from none of the common defects indicated in Table 1. Should 

 the ribbon not be coming perfectly, various suggestions given in Table 1 may 

 be tried until a perfect ribbon is secured. Since, in this case, a series of sections 

 is not needed, it is unnecessary to cut a longer ribbon than one which will 

 contain the actual number of sections required with a few left over for emer- 

 gencies. However, it is a great mistake to throw away partially cut blocks of 

 this nature since they may be stored in a glycerin-alcohol mixture quite indef- 

 initely, and one never knows when further sections may be required. The block 

 should be labeled before being placed in its solution. This is easily done by 

 writing the appropriate label on a piece of paper and fusing this into an un- 

 wanted portion of the block with a hot needle. 



Each individual section is now cut from the ribbon and mounted on the 

 slide in the way described on page 67; Before actually using Mayer's albumen to 

 mount the sections, it is necessary that the slides be cleaned. No two people 

 have ever agreed as to what is the most desirable method of doing this. The 

 author rubs the slide briskly with 1 per cent acetic acid in 70 per cent alcohol 

 and dries it by waving it in the air. Another method of cleaning the slide, 

 which yields equally good results, is given on page 49. After the sections are cut, 

 several drops of the diluted adhesive are placed in the center of each slide. 

 One of the individual sections is taken up with the tip of a moistened brush 

 and placed on the adhesive. As soon as the section has been placed on the 

 fluid, the slide is lifted up, warmed carefully over a spirit lamp until the sec- 

 tion is flat but the paraffin not melted, and then the superfluous liquid removed 

 carefully with the edge of a filter paper. One cannot in this instance, as though 

 he were mounting ribbons, drain the fluid from the corner of the slide. The 

 slide is put in a warm place to dry. If the drying period is to be prolonged, 

 it is well to place a dust cover over the slide since grains of dust falling 

 upon it will adhere just as tenaciously to the adhesive used as will the speci- 

 men itself. 



It is proposed in the present example to stain the slide in the simplest pos- 

 sible manner with celestin blue B followed by eosin. The formulae for these 

 stains will be found in Chapter 3. Of course, any of the other dyes recom- 

 mended there may be substituted. 



When the section is perfectly dry, it is turned upside down, and light is 

 reflected from it to see whether or not the section is adherent to the glass. If 

 there is any air gap between the section and the glass, a most brilliant mirror 

 will be formed, so that, in a preparation as simple as this, the slide had better 



