CHAP. 



DIGESTION. 



269 



ment membrane ; and of another different substance which occu- 

 pies the greater part of the cell. This latter substance is 

 composed of a loose network of fine fibres, the spaces of which 

 are occupied by a transparent material which does not stain 

 readily with carmine ; and upon examination is found to consist 



c 



FIG. 51. SECTION OF A. 'Mucous' GLAND, A in a state of rest, B after it has been for 

 some time actively secreting. (After Lavdowsky.) 



a demilune cells, c leucocytes lying in the inter-alveolar spaces. The darker 

 shading hi both figures is intended to indicate the amount of staiaing. 



largely of a material which is readily transformed into mucin, 

 and which may be spoken of as mucinogen or by abbreviation 

 mucigen. So that the ordinary mucous cell of a mucous gland 

 may be said to consist of a smaller portion of ordinary protoplasmic 

 substance and of a larger portion of a mucigenous substance. 



Such a condition of things exists however only in a mucous 

 cell at rest. When the gland is actively secreting, or rather after 

 the gland has for some time been actively secreting, as for 

 instance after the submaxillary gland of the dog has been subjected 

 to long and powerful stimulation of the chorda, a different state of 

 things presents itself when prepared sections of the hardened gland 

 are examined. The alveolus is then found to be made up of 

 smaller cells (Fig. 51 B) almost wholly formed of protoplasmic 

 substance readily staining with carmine. In extreme cases hardly 

 a trace is left of the mucigenous substance spoken of above ; in 

 cases of moderate activity cells may be seen in which the muci- 

 genous substance has diminished, with an increase of the ordinary 

 protoplasmic substance, but has not entirely disappeared. 



How are we to interpret these results ? obviously in this way. 

 The mucigenous basis is manufactured at the expense of the 

 ordinary protoplasm of the cell; the latter by its metabolism 

 produces the former and deposits it in the meshes of its own 

 framework, becoming as it were pregnant with mucigen. This 

 during the resting phase of the gland may go on to such an 

 extent, that only a small quantity of protoplasm is left to carry 



