100 THE SECRETIONS. 



tains much mucin, the fluid must be regarded as mucus ; if there 

 is no mucin in it, or only a small quantity, but on the other 

 hand much fat and albumen, it must be regarded as pus ; while 

 if all three are contained in the fluid, it must be regarded as 

 purulent mucus. In a veiy diseased state of the mucous mem- 

 brane the fluid may even contain fibrin, and thus resemble plastic 

 lymph. Henle 1 has observed this in one instance. We may 

 consequently observe the various stages of transition from plastic 

 lymph to the normal fluid of mucus (containing mucin, but 

 no albumen), in the same manner as we can trace the epithe- 

 lium-cells gradually downwards till they assume the form of 

 primary cells. 



The following conclusions are all that we are entitled to de- 

 duce from the previous observations : 



(1.) Pure mucus floats on water for a considerable time if 

 air-bubbles are entangled in it ; pure pus sinks rapidly to the 

 bottom ; purulent mucus swims if it contain air-bubbles, but 

 allows the pus to deposit itself; the deposit frequently takes 

 place in the form of pendent fibres. If pure mucus contain 

 no air-bubbles it sinks. 



(2.) Pure mucus, lying in water, appears as a homogeneous, 

 streaked, vesicular, viscid, and tenacious mass, of a white or 

 whitish-yellow colour, and yielding readily to pressure. Pure 

 pus forms a stratum at the bottom of water, of a white or 

 greenish-yellow colour, and sometimes tinged with blood; by 

 agitation it is diffused through the water, and in a short time 

 again sinks to the bottom. Purulent mucus forms streaked, 

 vesicular, often discoloured masses, or mucous sediments ; they 

 are easily diffused through water, and have a granular, non- 

 homogeneous appearance. 



(3.) Pure mucus imparts no albumen or mucin to water; 

 mucus which is mixed with much saliva does, however, render 

 water a little albuminous; pure pus communicates a large 

 amount of albumen to water, and purulent mucus imparts a 

 quantity of albumen proportionate to the amount of pus. 



None of what have been termed the " pus tests" are calcu- 

 lated, in my opinion, to detect minute quantities of pus in mu- 

 cus, and no test is requisite to distinguish pure mucus from 

 pure pus, or to recognise a large quantity of pus in mucus. 



1 Hufeland's Journal, 1836, p. 21. 



