MUCOUS SOFTENING. 31 



§ 39. The chemistry of mucous softening needs only a passinn- 

 mention at our hands. Taken broadly, it is founded on those 

 protean changes which the nitrogenous, histogenetic substances 

 undergo in the interior of our organism, and which manifest 

 themselves to us as so many variations on a given fundamental 

 theme, a theme for which our search has hitherto been fruitless. 



The soluble peptones and alkaline albuminates contained in 

 the gastro-intestinal tube are primarily converted into the seral- 

 bumen of the blood. This accompanies the nutrient fluid into 

 the parenchyma of all the organs, and, on becoming solid, serves 

 as material for the construction of the tissues. We find it, least 

 modified, in the protoplasm of the cells ; while the collagen and 

 chondrigen of the intercellular substances differ markedly from the 

 albuminates in their reactions, and may hence be termed albu- 

 minoids. The transformation into mucin which collao-en and chon- 

 drigen undergo during mucous softening, renews their afiinities 

 with albumen ; mucin, however, contains no sulphur ; in other 

 respects it exhibits an unmistakable analogy to the albuminates, 

 both in its elementary constitution and in its behaviour towards 

 alkalies. All natural solutions of mucin have an alkaline reac- 

 tion ; indeed mucin is soluble only when combined with a free 

 alkali. For if a solution of mucin is treated with acetic acid it 

 grows viscid in proportion to the amount of alkali neutralised, 

 until at length it separates in thick flakes. It is this last pro- 

 perty which more especially connects mucin with the albuminates. 

 For these, too, occur only in the alkaline fluids of the organism, 

 and we know that some pai't of them at least is held in solution 

 by free alkali. This part behaves almost like an organic salt, in 

 which the place of the acid is taken by the albuminous body 

 (acid-albumin of Fanum) ; hence it is termed alkaline, or sodic 

 albuminate. 



True sodic albuminate thus constitutes the first and last mem- 

 ber of the series of metamorphoses associated with mucous soften- 

 ing. This gives a high degree of probability to that affinity 

 between mucin and the albuminates on which I have already laid 

 stress. 



Sodic albuminate differs from ordinary albumen by its greater 

 solubility in water, and also by the greater readiness with which 

 it parts with its water. If crystals of common salt are placed in 

 a fluid containing an alkaline albuminate, the latter separates as 



