72 THE SECRETIONS: 



is examined under the microscope, it is found to consist of a 

 liquid in which minute rounded or prolonged corpuscles of a 

 granular appearance (mucus-corpuscles) are inclosed, which do 

 not exhibit any independent motion, in consequence of the thick 

 viscid nature of the fluid in which they are suspended; hut when 

 the fluid is stirred they are seen to move with it. In addition 

 to the mucus-corpuscles, some epithelium-cells are also observed, 

 and a finely- granulated substance which pervades the whole 

 fluid; and can only be seen with a good light. Nasal mucus, 

 from my own observations, is represented in fig. 15 ; a a mucus- 

 corpuscles, b b epithelium cells; c c the faintly granular 

 substance. 



According to Henle, the diameter of the mucus-corpuscles 

 varies from 0-003 to 0-007 of a line : according to Vogel, from 

 0-004 of a line : Gruby 1 considers them from 2 to 4 times the 

 size of the blood-corpuscles. They are prolonged, oval, or 

 round, and when observed in fresh mucus have a clear well- 

 defined contour, a pale gray colour, a granular appearance, and 

 sometimes give faint indications of one or more nuclei. After 

 remaining for some time in water, the mucus- corpuscles become 

 more or less swollen, paler, and more transparent ; the granular 

 appearance on the external capsule disappears, and one or more 

 nuclei may be observed in the interior of the cell. The external 

 capsule frequently becomes so colourless as to render its de- 

 tection difficult. 



The epithelium-cells appear under the microscope in the form 

 of elliptic discs ; according to Gruby, the axis major varies from 

 0-013 to 0-0333 of a line, and the axis minor from 0-010 to 

 0-016 of a line : the surface is frequently irregular, wrinkled, 

 or plicated. We sometimes find them swollen and vesicular, 

 and sometimes, but more rarely, almost circular or elliptic. The 

 nucleus is of the same prolonged form as the mucus- corpuscle; 

 it is granular and rather darker coloured. If mucus is fre- 

 quently observed, the transition of mucus-corpuscles into epithe- 

 lium-cells may easily be seen. ~VVe have attempted to illus- 

 trate this progressive change in d, e,f, fig. 15. 



1 Qhservationes Microscopicae ad Morphologiam Pathologicam. Vindobonse, p. 15. 



