134 PRACTICAL HISTOLOGY. 



Preparation 8. The structure of the tunics 

 which form the lamellated capsule of the Pacinian 

 body is not well shown in the fresh preparation, 

 owing to the transparency of the object ; indeed, 

 it is the lines of contact between successive coats 

 which look like layers of the capsule ; the substance 

 of the coat being clear and pellucid, gives the notion 

 of an intermediate fluid. In order to show their 

 fibrous connective tissue structure (the white fibrils 

 running transversely, and collected for the most 

 part near the surfaces of each tunic, and the elastic 

 fibrils forming a network through the thickness) 

 some of the little bodies should be dissected out in 

 the way above described, -and placed for ten days or 

 a fortnight in a per cent, solution of chromic acid. 

 They are then placed on a slide in a drop of water, 

 and with fine and perfectly clean needles are broken 

 up under the dissecting microscope bit by bit, com- 

 mencing at one end and breaking off transverse 

 pieces. It will be found that, owing to the direction 

 of the fibrils, the corpuscles tend to break across 

 into disk-like portions. The core does not share 

 this tendency, but this is of little consequence, for 

 it is not well displayed in these preparations. A 

 piece of hair having been added, the preparation is 

 covered and examined. Small fragments will pro- 

 bably be found which give a sectional view of the 

 tunics, and others in which they are seen fiat. If 

 a little logwood solution is allowed to run under 

 the cover-glass, nuclei on the surface of the tunics 

 may here and there be stained. 



Preparation 9. These nuclei belong to flattened 

 epithelioid cells, which cover both outer and inner 

 surface of each tunic, and which, seen in profile, are 

 in reality the well-defined lines seen in the fresh 

 Pacinian, and long described as the coats themselves. 

 The outlines of these cells may be brought into view 

 by staining with nitrate of silver. For this purpose, 

 as is always the case with silver-preparations, the 

 tissue must be fresh and unacted on previously by 



