Microfome Sectioning of Material in Paraffin 53 



known position in the loaf. A iinitorm system of placing the sections 

 and numbering the slides should be worked out and rigidly followed. 

 A convenient method is to place the strips of ribl^on so that the 

 sections follow the order used in writing, as tollows: 



The foregoing numbers show the successive order of the sections 

 of a seriation as they are attached to a slide. However, a convenient 

 method of designating any given section on the above slide is as 

 follows: 



(Row 1) 12 3 4 5 

 (Row 2) 1 2 [3] 4 5 

 (Row 3) 1 2 3 4 5 



The bracketed section is designated as roiv 2, section 5. The numbers 

 2-3 on the label enable the observer to relocate the section quickly. 

 A block of tissue may yield so much ribbon that several slides 

 are recpiired to mount the ribbon. In such cases seriation is main- 

 tained by mounting the ribbon on the first slide as described above. 

 On the second slide section 16 occupies the upper left hand position as 

 follows: 



Slide 1 Slide 2 



12 3 4 5 16 17 18 19 20 



6 7 8 9 10 21 22 23 24 25 



11 12 13 14 15 26 [27] 28 29 30 



The number of sections placed on a slide depends on the space 

 available on the slide, the size of the sections, their spacing in the 

 ribbon, and the size of the available cover glasses. Individual sections 

 on any slide are designated by row and section in that row. The 

 bracketed section, which is actually twenty-seventh in the seriation, is 

 identified by the designation slide 2, row 5, section 2. Each of the 

 slides in a seriation should be engraved or marked with marking ink, 

 giving the code number of the lot or collection of embedded material, 

 the number of the piece taken out of that lot, and the number of the 

 slide in the seriation. As a specific illustration, assume that from 

 embedded batch 1 of apple leaf you have removed a piece of leaf 

 (piece 1) and sectioned it, and obtained enough ribbon to fill three 

 slides, with sections in serial order. The slides are numbered 1-1-1, 

 1-1-2, 1-1-3, meaning, in the last instance, batch (lot) 1, piece 1, 

 slide 3. An individual section on slide 3 is then completely identifiable 



