30 NORMAL HISTOLOGY. 



fluid or Flemming's fluid (formula b, page 5) for 

 twenty-four hours. It is then soaked for an hour in 

 water to remove the chromate solution, and the now 

 loosened cells are scraped from the surface of the mu- 

 cous membrane and placed in a few cubic centimetres 

 of the picro-carmine solution, where they remain until 

 they have acquired a distinct red color. A small frag- 

 ment of the cell mass is now transferred to a slide, 

 covered with a drop of glycerin, teased apart with 

 needles, and carefully covered with thin glass so as to 

 exclude all bubbles of air. The cover-glass should be 

 allowed to close down upon the specimen by its own 

 weight alone, since much pressure upon these delicate 

 cells distorts and breaks them. This, like nearly all 

 specimens, should be examined first with a low and 

 then with a high power. The cells will be found to 

 have a great variety of forms, some of them evidently 

 determined by the pressure of adjacent cells. They have 

 a finely granular body, with more coarsely granular nu- 

 clei, and nucleoli. In many cases, instead of appearing 

 coarsely granular, the nucleus is seen to contain a distinct 

 reticulum (intranuclear network} of strongly refractive 

 material, the thickened nodal points of which may be 

 regarded as nucleoli. To preserve this, and all specimens 

 mounted in glycerin, a narrow rim of asphalt varnish is 

 painted around the cover-glass, lapping over the edges of 

 the latter and extending for a short distance on to the 

 slide. 



Pigmented Cells of the Retina. An eye from the ox or 

 sheep, which has lain for a few days in Miiller's fluid, is 

 opened by an equatorial section, and the vitreous body 



