136 PRACTICAL HISTOLOGY. 



are severed close to their attachments, so as to get 

 them in their whole length, and the small, thin 

 piece of muscular tissue obtained is quickly trans- 

 ferred to a slide, and mounted, either without addi- 

 tion of fluid or in a small drop of serum which is 

 put on the cover-glass before this is inverted over 

 the preparation. 



This should now be thoroughly searched with a 

 good immersion objective for the nerve endings. 

 Branches of the intercostal nerve will be found 

 running across the direction of the muscular fibres. 

 Starting from one of these, trace carefully one by 

 one the single nerves which pass off from it. It will 

 be found generally that they branch one or more 

 times, and eventually the resulting twigs pass off to 

 the muscular fibres, each fibre receiving one of the 

 nerve-twigs. They retain their medullary sheath 

 until the muscular fibre to which they are attached 

 is reached, when the sheath suddenly ceases to be 

 visible, and it is by following the single fibres until 

 they come in this way to an abrupt termination, 

 that an end-plate may be met with. But even if the 

 place where the nerve-fibre joins the muscular fibre is 

 arrived at, it is still in most cases difficult to make 

 out the exact mode of termination, in other words, 

 the structure of the plate. The utmost that can 

 generally be seen is a clump of clear, round nuclei 

 embedded in a granular meterial. The difficulty 

 arises partly from the readiness with which these 

 structures undergo alteration after removal in warm- 

 blooded animals, and partly from the fact that they 

 are often obscured by super- and sub-jacent muscular 

 fibres or bloodvessels. 



Preparation 12. In the common lizard (Lacerta 

 agilis) the end-plates may be much more easily 

 found and satisfactorily seen, but still the utmost 

 care must be taken in the preparation. The animal 

 having been decapitated and the trunk pinned out 

 upon a cork, a piece of one of the limb-muscles 

 including the whole length of the fibres is removed 



