428 RETROdUEiiiiiyE CUAXGES 



tlie confined spaces of the tumor. Tlie mucin in these forms of mucoid 

 (k^gencration is cliemically tlie same as the normal mucin coming from 

 the same source, but mixed with larger or smaller quantities of other 

 proteins derived from cell degeneration or from vascular exudates, 

 and we do not yet know certainly the chemical character of the secre- 

 tion of iioi'mal mucous monibranos.-'"' (The stringy, mucin-like sub- 

 stance seen in some purulent exudates is probably composed largely of 

 nueleoproteins and nucleo-albumins derived from the degenerating 

 leucocytes, and is not true mucin.) 



Connect! ve=tissue Mucin. — Excessive formation of connective-tis- 

 sue mucin is observed most characteristically in myxedema {q. v.), 

 but may also occur in connective tissues that are poorly nourished or 

 otherwise slightly injured ; it is seen particularly in the connective 

 tissues surrounding the epithelial elements in adenomas and carcino- 

 mas. In the walls of large blood vessels there is a mucoid connective 

 tissue, rich in mucin, which may be increased in arterio-sclerosis 

 (Bjorling).-^ Connective-tissue tumors (myxosarcoma, myxofibroma, 

 or myxoma) may also show a great quantity of mucinous intercellular 

 substance, but many of the so-called myxomas are in reality merely 

 edematous fibromas or polypoid tumors, in which the resemblance to 

 true myxoma is largely structural rather than chemical. This form 

 of mucoid degeneration seems to be merely a reversion to the fetal type 

 of connective tissue, which is characterized, as in the umbilical cord, bj^ 

 an excessive accumulation of a mucin-containing fluid intercellular 

 substance, and a paucity of collagenous fibrillar structure. Appar- 

 ently, when connective tissue reverts to an embryonal type, either 

 from intrinsic causes (tumor formation), or when the nourishment 

 is insufificient, or possibly when the normal stimulus to cell growth is 

 absent (myxedema), the mucoid characteristics of fetal tissue reappear. 



The presence of mucin in the tissues seems to cause no reaction, 

 and its absorption causes no harm. Rabbits that I injected with 

 large quantities of pure tendon mucin almost daily for two to four 

 months, showed absolutely no deleterious effects, either locally or con- 

 stitutionally. Some of the French authors -- claim that mucin pos- 

 sesses a slight bactei'icidal power. On the other hand, Rettger -^ and 

 others have found an apparently typical mucin produced by certain 

 varieties of bacteria. 



GLYCOGEN IN PATHOLOGICAL PROCESSES -* 



It seems probable that all, or nearly all, cells contain larger or 

 smaller quantities of glj^cogen, but it may be insufficient in amount 



20b See Lopez-Suaroz, Bioehcm. Zoit., 101.3 (56), 107. 



21 Vircliovv's Arohiv., ]!»]] (2().")), 71. 



22 Arloinsr. Compt. Tlond. Soo. Biol.. 1002 {TA), .100. and 1001 (53). 1117. 



23 .Tour. :\Ic(l. Bcsoarcli, 100.3 (10), 101. 



24 Biblidfrrapliv by fliorko, Ziosrlor's Boiir.. 1005 (.37). 502, and Ergcbnisse 

 Pathol., 1007, Xi(j)", 871; Klosfadt, ibid., 1011 (XV(,), .349. 



