MOTOR END-PLATES. 



and placed on a slide in a drop of serum. The fibres 

 are then isolated under the dissecting microscope as 

 carefully and completely as may be, and a piece of 

 paper or a hair having been added to avert pressure 

 on the tissue, it is covered and the fibres are ex- 

 amined with an immersion along their whole length. 

 Of course, if no end-plates can be found in the first 

 specimen another must be taken, but it will gene- 

 rally not be very long before one is found, either at 

 the edge of a fibre, and therefore seen in profile, or 

 on the surface, and seen flat. 



Unfortunately, a method has not yet been dis- 

 covered by which they may be well preserved. That 

 which on the whole answers the best is to treat the 

 preparation with 1 per cent, osmic acid, having first 

 washed away the serum by salt solution. After tho 

 osmic has been about an hour in contact with the 

 tissue, it may be washed away and glycerine sub- 

 stituted. In this way the form of the little end- 

 plate or prominence is well preserved, and the 

 sudden termination of the medullary sheath of the 

 nerve fibre well shown, since this becomes blackened 

 by the osmic acid, but the substance of the end-plate 

 becomes dark and granular, so that the nuclei are 

 with difficulty seen. 



12* 



