CH. VII] 



COILODION SECTIONING 



179 



two millimeters all around the tissue. This is to render the diameter of the end to 

 be cut as small as possible. The smaller the object the thinner can the sections be 

 made. With an object two or three millimeters thick and not over five milli- 

 meters wide, and a good sharp knife, sections 5// to 6/c can be cut without diffi- 

 culty. When knife and tissue are properly arranged the tissue and the knife are 

 flooded with the clarifier. Make the sections with a steady motion of the knife. 

 Then draw the section up toward the back of the knife with an artist's brush and 

 make the next section. Arrange the sections in serial order on the knife blade 

 till enough are cut to fill the area that the cover-glass will cover. For large objects 

 one can cut thinner sections by a kind of sawing cut. 



\ 275, Transferring the Sections to the Slide. — If the clarifier has evaporated 

 so as to leave the sections somewhat dry on the knife, add a small amount. Take 

 a piece of thin absorbent, close-meshed paper about twice the size of a slide and 

 place it directly upon the sections. Press the paper down evenly all around and 

 then pull the paper off the edge of the knife. The sections will adhere to the 

 paper. Place the paper, sections down, on a slide, taking care that the sections 

 are in the desired position on the slide. Use some ordinary lens paper or some 

 absorbent paper, and press it down gently upon the transfer paper. This will ab- 

 sorb the oil, and then the transfer paper may be lifted, with a rolling motion, 

 from the slide. The sections will remain on the slide. (See notes p. 180). 



\ 276. Fastening the Sections to the. Slide. — Drop just enough ether- 

 alcohol (equal parts of sulphuric ether and 95% alchol) on the sections to moisten 

 them. This will melt the collodion and fasten the sections to the slide. Allow the 

 slide to remain in the air till the surface begins to look slightly dull or glazed. 



Sometimes, especially when the air is moist, the sections wrinkle badly when 

 the ether-alcohol is put on to fasten them to the slide. The excessive wrinkling 

 can be avoided by using one part alcohol and two parts ether instead of using 

 equal parts of each. Perhaps also it would be advantageous in this case to use 

 absolute alcohol. 



Fig. 147. Reagent bottle with combined cork and pipette {This 

 is made by taking a cork of the proper size and making in it a hole 

 with a cork borer for the glass tube. It is advantageous to have a 

 string tied tightly around the rubber bulb as shown). 



\ 277. Removing the Oil from the Sections. — As soon as the 

 ether-alcohol has evaporated sufficiently to leave the surface dull, 

 place the slide in a jar of ordinary commercial benzin. It may be 

 left here a day or more without injury to the sections, but if 

 moved around in the jar the oil will be removed in three to five 

 minutes. From the benzin transfer to a jar of 95Q-0 alcohol to 

 wash away the benzin. One may use alcohol in the beginning, 

 but it dissolves the oil far less rapidly than the benzin. The slide 

 may remain in the alcohol half a day or more if one wishes, but a 

 stay of five minutes or a thorough rinsing of half a minute or so 

 by moving the slide around in the alcohol will suffice. 



Xylene is to be preferred to benzin for removing the oil, but 

 it is more expensive. 



Fig. 147. 



