CONNECTIVE TISSUE. 49 



ing and pulling of the membrane should be avoided, be- 

 cause this would destroy the natural relations of the cells 

 to one another. The membrane must be allowed to sag 

 a little into the dish, so that it may be bathed on both 

 sides by the silver solution. It is now to be carefully 

 washed with water to remove any albuminous substance 

 or blood which wo.uld cause a granular precipitate of 

 silver albuminate on the surface and the dish then filled 

 with an aqueous solution of nitrate of silver, i to 500. 

 The dish should be gently shaken at frequent intervals, 

 so as to bring fresh portions of the solution into contact 

 with the membrane, and after from twenty minutes to 

 half an hour the tissue will be seen to have become 

 cloudy or milky. 



The silver is now poured off, and the membrane care- 

 fully washed with water. The cells will have been fixed 

 by the silver, so that the membrane may be removed 

 without further danger of disturbing the relation of the 

 cells, and laid in a dish containing water to which one 

 third its bulk of alcohol has been added. It is now ex- 

 posed to the sunlight, and after from a few minutes to 

 half an hour sometimes longer, depending upon the 

 intensity of the light the tissue will be seen to have 

 assumed a brown color. 



A small piece from the thinner portion should now 

 be lightly stained with haematoxylin and mounted in 

 glycerin. 



These portions of the mesentery consist of a thin mem- 

 brane of fibrillar connective tissue containing a delicate 

 network of elastic fibres and a few small blood-vessels ; 

 the whole being covered on both sides by the delicate 

 4 



