160 COLLODION SECTIONING. [CH. VII. 



§ 259. Cutting the Sections. — For collodion sectioning a long, draw- 

 ing cut is necessary in order to obtain thin, perfect sections. The ob- 

 ject is, therefore, put in the jaws of the microtome at the right level, 

 and the knife arranged so that half or more of the blade of the knife is 

 used in cutting the section. It is advantageous also to have the object 

 placed with its long diameter parallel with the edge of the knife. The 

 surrounding collodion mass should be cut away, as in sharpening a lead 

 pencil, so that there is not more than a thickness of about two millime- 

 ters all around the tissue. This is to render the diameter of the ena to 

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

 sections be made. With an object two to three millimeters thick and 

 not over five millimeters wide, and a good sharp knife, sections 5/u. to 

 6/j. can be cut without difficulty. When knife and tissue are properly 

 arranged the tissue is well wet and the knife 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. 



§ 260. 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 pa- 

 per* about twice the size of a slide and place it directly upon the sec- 

 tions. Press the paper down evenly all around and then pull the paper 

 off the edge of the knife, t 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 any 

 absorbent paper, and press it down gently upon the transfer paper. 

 This will absorb the oil, and then the transfer paper may be lifted, with 

 a rolling motion, from the slide. The sections will remain on the slide. 



S 261. Fastening the Sections to the Slide. — Drop just enough 



* Various forms of paper have been used to handle the collodion sections. It 

 should be moderately strong, fine meshed and not liable to shed lint, and fairly ab- 

 sorbent. One of the first and most successful papers recommended is "closet or 

 toilet paper." Cigarette paper is also excellent. In my own work the silky Japa- 

 nese paper, called " Usago" paper, has been found almost perfect for the purpose. 

 Ordinary lens paper or thin blotting paper for absorbing the oil is used with it. 



t If one is a long time cutting a series of sections, it sometimes occurs that the 

 xylene evaporates, and while the sections may not look dry, they are practically 

 in castor oil and not easily transferable. In such a case fresh clarifier or even 

 a little xylene to thin the oil on the sections may be used. If the oil is too thick 

 it is viscid and there is difficulty in handling the sections with the paper as they 

 stick rather firmly to the knife. 



