156 EXUDATIONS. 



of albumen in the serum of the pus is very variable, according to 

 the source from whence it is derived ; in the four analyses which I 

 was alone able to make, I found from 1'2 to 3'?% of albumen in the 

 serum of the pus of different persons. 



Mucin is not present in pus, except the latter has been 

 obtained from inflamed mucous membranes ; it may in general 

 be easily distinguished by a microscopical examination of the pre- 

 cipitate from other substances, which are precipi table by acetic acid. 

 It presents an appearance of whitish striped flakes or membranes 

 (see vol. ii, p. 371). 



Pyin is a substance which is in like manner precipitable by 

 acetic acid, although it differs from mucin as much as from casein. 

 This substance which was first shown by Giiterbock* to be present 

 in pus, is not of constant occurrence ; it is certainly absent from 

 the pus of wounds in healthy persons. Giiterbock obtained it 

 from the pus by coagulating the latter with alcohol, and extracting 

 the residue with water; it is remarkable for being precipitable 

 with acetic acid and a solution of alum, whilst it remains perfectly 

 undissolved in both these fluids. Notwithstanding the frequent 

 notices of this substance in works treating of pus and mucus, it 

 has been very imperfectly investigated. Mistakes may, however, 

 easily be made; thus, for instance, on coagulating the pus, the 

 fluid becomes more strongly alkaline ; the alkali dissolves a portion 

 of the coagulated albumen, and this solution, when acted upon by 

 acetic acid, deposits a considerable precipitate, but this latter does 

 not dissolve in an excess of acetic acid as rapidly as one might 

 have been led to expect from the assertions of most writers. A 

 mistake may, therefore, easily occur even when the absence of 

 mucus or casein can be demonstrated ; the latter point is not very 

 easy of proof, except in some special cases. Schererf has sub- 

 mitted pyin-like bodies to elementary analysis, and in the course of 

 these observations he found that what had been regarded as a simple 

 substance, and supposed to be pyin, consists in fact of very various 

 substances with the most different composition. Many persons 

 have considered pyin to be an oxide of protein, indeed, as Mulder's 

 tritoxide of protein ; but it will be found on a closer examination 

 that the reactions of pyin do not correspond better with this 

 substance than Scherer's elementary analyses of the latter do with 

 Mulder's analysis of the tritoxide. Many authors are of opinion 

 that pyin may be a transition-stage from fibrin to gelatigenous 



* De puns natura et formatione ; diss. inaug. Berol. 1837. 

 t Untersuchungen zur Pathologie, S. 85-96. 



