432 RETROGRESSIVE CHANGES 



vascular exudates, and we do not yet know certainly the chemical 

 character of the secretion of normal mucous membranes." (The 

 stringy, mucin-like substance seen in some purulent exudates is prob- 

 ably composed largely of nucleoproteins and nucleo-albumins derived 

 from the degenerating leucocytes^ and is not true mucin.) 



Connective=tissue Mucin. — Excessive formation of connective- 

 tissue 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 j&bromas 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, 

 by 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 insufficient, 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 bactericidal 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 glycogen, but it may be insufficient in amount 

 to be detected either microscopically or chemicall3^ Glj^cogen seems 

 to be formed within the cells from the sugar of the blood, through a 

 process of dehydration and polymerization, and to be reconverted 

 whenever necessary into sugar, by a reverse process of hydrolysis. It 



^^ See Lopcz-Suarez, Biochcm. Zeit., 1913 (56), 167. 

 ^* Virchow's Archiv., 1911 (205), 71. 



"ArloiiiK. Coinpt. Rend. Soo. Biol., 1902 (54), 306, and 1901 (53), 1117. 

 ^« Jour. Med. Research, 1903 (10), 101. 



" Bibliography by Gierke, Ziegler's Beitr., 1905 (37), 502, and Ergebnisso 

 Pathol., 1907, XI (2), 871; Klestadt, ibid., 1911, XYU), 349. 



