INVOLUNTARY MUSCLE. 113 



quite dilute, and suffered gradually to diffuse itself 

 under the cover-glass from a small drop placed at 

 one edge. It is not a good plan to draw it through 

 by means of blotting-paper, since in this way many 

 of the isolated elements of the tissue will be drawn 

 away at the same time. But after the drop of log- 

 wood solution has passed in great measure or entirely 

 under the cover-glass, a small drop of strong glyce- 

 rine may be added at the same spot as the logwood. 

 This as it diffuses under the cover will gradually 

 push, as it were, the logwood solution before it, so 

 as to cause the staining fluid to traverse successively 

 every part of the preparation, and eventually to 

 become collected entirely at the opposite edge, the 

 water meanwhile evaporating and leaving the glyce- 

 rine in possession of the field. All that is needed 

 to complete the preparation is, in the course of a day 

 or two, to fix the cover-glass by painting a little 

 chloroform balsam around the edges. 



The involuntary muscular fibres will be seen in 

 section in preparations of the stomach and intestine 

 and numerous other organs, so that it is not neces- 

 sary to make special preparations at this stage for 

 the purpose. It may, however, be instructive to 

 demonstrate the manner in which the cells are 

 applied edge to edge in order to make up the 

 bundles and lamellae of the tissue. This is often 

 shown sufficiently well in a thin strip which has 

 been stained with logwood and mounted in glyce- 

 rine without teasing. 



Preparation 2. But the best preparations for 

 exhibiting the arrangement of the cells are those 

 stained with nitrate of silver. As in other tissues, 

 this reagent stains only the intercellular substance, 

 leaving the cells themselves uncolored ; their out- 

 lines are thus brought very distinctly into view. 

 The way to prepare the muscular coat of the intes- 

 tine by this method is as follows : A piece of intes- 

 tine is removed from the recently-killed animal (the 

 large intestine of the frog answers verv well for the 



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