278 HISTOLOGY OF THE MORBID PROCESSES. 



its production may involve a destruction of the cytoplasm, which 

 appears to be sacrificed. A similar transformation or replacement 

 of the normal intercellular substances may also occur in the connec- 

 tive tissues, such as bone, cartilage, fat, or fibrous tissue, which then 

 contain more than the normal proportion of mucin. This propor- 

 tion may be so great as to alter the physical properties of the tissue. 

 In these cases the cells may undergo mucous degeneration, or they 

 may ultimately suffer a fatty degeneration. It is a question to what 

 extent the cells are active in the substitution of mucous for the usual 

 intercellular substances, the manner in which it is produced being 

 as yet undetermined. 



The mucus is a clear, viscid fluid, which appears to be a mixture 

 of various substances containing either mucin or pseudomucin. 

 These substances are precipitated by alcohol, so that in hardened 

 specimens the mucus becomes granular or is streaked with linear 

 coagula. Hsematoxylin usually stains the whole mass a faint blue ; 

 the granules and streaks a little more intensely than the clearer por- 

 tions. This staining serves to distinguish the mucus from a serous 

 fluid, which is also made granular by the coagulating influence of 

 alcohol upon the albumin it contains. 



Mucous degeneration of the epithelia is a frequent accompani- 

 ment of inflammation of the mucous membranes, where it appears to 

 be due to an excessive stimulation of the functional activities of the 

 cells. A similar mucous degeneration of epithelial cells is also very 

 common in tumors ; e. g., the cystomata of the ovary and colloid 

 cancer. 



7. Colloid Degeneration. This is a form of degeneration in which 

 the substance of cells is converted into a clear, homogeneous, gelat- 

 inous material of greater consistency than mucus, and, unlike the 

 latter, is not precipitated by alcohol, so that in hardened specimens 

 it retains its homogeneous appearance. 



The production of colloid seems to be normal in the thyroid 

 gland after the attainment of a certain age. In this situation the 

 colloid material is formed in the cells of the alveoli and then dis- 

 charged into their lumina, Avhere it forms a mass that may com- 

 pletely fill its cavity (Fig. 154) ; but the cells of the thyroid not 

 infrequently suffer destruction in the elaboration of the colloid 

 material, so that even here the process partakes of a degenerative 

 character. 



The material forming the hyaline casts in various kinds of 



