CELLS OF TENDON. 85 



tendon bundles, are too delicate to be made out 

 without staining. In some of the chains a bright 

 longitudinal line is to be seen on each cell ; this ap- 

 pearance is merely produced by a lamellar prolonga- 

 tion of this sort, which happens to extend vertically 

 to the plane under observation. 



After the action of the acid has been prolonged 

 for some time, the cells gradually lose their dis- 

 tinctness, and eventually can with difficulty be 

 made out, although the iibres are more swollen and 

 indistinct than ever. But if a little of the colored 

 acetic acid which was used for the subcutaneous 

 tissue (Prep. 4) is allowed to run under the cover- 

 glass, first the nuclei, and then the bodies of the 

 cells and their prolongations, become colored, whilst 

 the fibres remain unstained, just as in the parallel 

 case of the areolar tissue. 



When the coloration is sufficiently deep, the 

 staining fluid may be replaced by water, and this 

 in the usual way by glycerine ; and finally, the edges 

 of the cover-glass being cemented, the preparation 

 can be permanently preserved. Examined with a 

 high power, the tendon cells now appear in the suc- 

 cessive horizontal planes as quadrangular flattened 

 bodies, thickest near the middle, and gradually 

 shading off at either side, and marked with one or 

 more dark lines running longitudinally, which are, 

 in fact, the bright lines to which attention was pre- 

 viously drawn, and which have now become stained. 

 To show that these are actual flattened extensions 

 of the cell, and not mere markings, it is necessary to 

 compare the appearances presented by a transverse 

 section. 



Another method of displaying the cells of tendon is 

 that originally employed by Ranvier. One or two of the 

 small tail tendons are placed on a slide, and their ends 

 are fixed with paraffin, so as to keep them extended. A 

 few drops of one per cent, solution of picrocanninate of 

 ammonia are then placed upon them and left for half an 

 hour, after which the picrocarmme is washed away with 

 8 



