PRODUCTS, ADVENTITIOUS. 



The various appearances of pus have given 

 rise to its classification into the creamy, 

 curdy, serous, and slimy varieties (Pearson) ; 

 one obviously unfit to represent the existing 

 state of knowledge. It seems better to con- 

 sider pus as of two kinds : I. Simple; II. With 

 added characters, the added character being 

 derived either from (A) Substances of known 

 nature, natural or morbid ; or from (B) Sub- 

 stances of unknown nature, called viruses. 



The pus-corpuscle has uniformly the same 

 character in all descriptions of pus. The dis- 

 tinction of the varieties above enumerated, 

 therefore, can only be microscopically effected 

 (if it can be effected at all) by means of su- 

 peradded elements ; and most valuable these 

 are as diagnostic of its seat and production in 

 many instances. 



The varieties of pus comprehended in the 

 class (B), differ from those in the class (A), 

 in being inoculable, a character dependent 

 not upon any peculiarity of their cell, but 

 upon the associated intangible " virus." Some 

 of the varieties of the class A possess, how- 

 ever, what may be called pseudo-inoculability, 

 namely, those in which certain parasites are 

 present. The pus of scabies is thus to be 

 propagated by means of its entozoon ; that of 

 porrigo by its entophyte ; but it is clear that 

 the associated pus has in reality nothing to do 

 with the transmissibility of the diseases.* 



There are three semi-fluid matters, which it 

 is important to distinguish from pus, namely, 

 mucus, softened fibrin, and fluid holding epithe- 

 lium in suspension. The distinctive characters 

 most to be relied on are as follow: (a) Mucus. 

 (1.) Pus mixes with water, being at first 

 equally diffused through it, so as to give it a 

 yellowish tinge ; subsequently, the corpuscles 

 fall to the bottom, and leave the supernatant 

 fluid clear and colourless. Mucus does not 

 mix with water, but eventually renders it 

 slimy. (2.) Pus forms an emulsion with 

 acetic acid, from which, after a time, the 

 nuclei of the corpuscles are thrown down as 

 a yellow sediment, while the involucra are 

 dissolved. Mucus is coagulated by acetic 

 acid, and forms a membranous flocculent mass 

 without mixing with the acid; at the same 

 time it becomes less slimy and more con- 

 sistent. (3.) Pus forms a ropy mass with 

 the caustic alkalies, or with their carbonates. 

 (B. Babington.) Mucus, on the contrary, 

 is rendered thinner, and partially dissolved 

 by them. (4.) Pus contains fat removeable 

 by ether, sometimes in such quantities as 



* Donne describes an animalcule, under the name 

 of Tricomonas vaginalis, as peculiar to the female 

 syphilitic discharge, and constituting the infection- 

 agent. But it is not found in the male, and is often 

 absent in the female ; its powers in the latter quality 

 may be more than doubted. Froriep (Notizen, 1837, 

 No. 25. p. 40.) thinks the animalcule, peculiarly 

 connected with the female genitals, but not specially 

 with syphilis ; and regards it with Ehrenberg (No- 

 tizen, 1837, No. 28. p. 88) as a species of acarus. 

 This matter requires revision ; it has even been sug- 

 gested that Donne' and his followers have mistaken 

 ciliated epithelium-scales (to which indeed the figure 

 of the former bears much resemblance) for animal- 

 cules. 



to render it inflammable; mucus contains 

 none. (5.) Air bubbles in pus collapse the 

 moment they are formed ; in mucus they re- 

 main for a time for days even unaltered. 

 (6.) Equal parts of concentrated sulphuric 

 acid and pus form a dull brown-red solution, 

 becoming paler and turbid by the addition of 

 water ; mucus, on the contrary, forms a pale 

 brown fluid with this acid, which remains clear 

 and becomes colourless on the addition of 

 water. (Brett and Bird.) (7.) According 

 to Preuss, pus (as also tubercle) is distin- 

 guishable from mucus by containing iron 

 (which may be shown by inceration and di- 

 grating the ash in gum, hydrochloric acid, di- 

 luted with five parts of distilled water, and 

 then adding a few drops of ferro- cyanide of 

 potassium) : but in point of fact the presence 

 of iron is due to accidental admixture with 

 blood. (8.) Pus pressed between two plates 

 of glass and held before a candle, presents an 

 iridescent appearance ; no such effect is ob- 

 served with mucus. (Young ) The state of 

 knowledge concerning the two alleged prin- 

 ciples, mucin and pyin, is too unsettled to 

 allow of just inferences being drawn from the 

 presence or absence of either. 



Various attempts have been made to dis- 

 tinguish pus and mucus by means of the proper 

 corpuscle of each. The difficulty experienced 

 in the detection of distinctive characters gra- 

 dually led to the suspicion that the corpuscle of 

 both fluids might be one and the same thing ; 

 and the inquiries of several competent persons 

 appear at length to have distinctly established 

 the fact, that healthy mucus contains no special 

 corpuscle, but that, under the very slighest 

 irritation of a mucous surface, pus, with its 

 special cell, is thrown out, which cell had been 

 mistaken for one peculiar to the natural secre- 

 tion of mucous membranes. The presence of 

 a bougie in the urethra for a very short time 

 suffices to cause the production of muco-pus* 

 The abundance of epithelium-scales in mucus 

 is sometimes a useful aid in the diagnosis : 

 the nuclei of these scales set free may, doubt- 

 less, also have been sometimes mistaken for 

 special corpuscles. 



(b.) Softened Fibrin. The semi-liquid 

 matter frequently found in the centre of co- 

 agula in the veins and heart, was long con- 

 founded (from its colour, consistence, and 

 easy miscibility with water,) with pus ; noto- 

 riously so by MM. Gendrin, Andral, Cruveil- 

 hier, and Magendie. It had been more or 

 less confidently affirmed, however, by MM. 

 Dupuytren, Burrows, Davy, and others, that 

 this matter really consisted of softened fibrin, 

 and not pus, when Mr. Gulliver-)- gave support 

 to this notion by pointing out the following 

 peculiarities, distinguishing the substance in 

 question from pus : 1. It is not rendered ropy 

 by caustic volatile alkali. 2. It presents no 

 iridescence when pressed between plates of 

 glass before a candle. 3. Under the micro- 



* That is as far as the generation of pus-corpuscles 

 is concerned ; the production of liquor puris is a more 

 elaborate process. 



+ Med. Chir. Trans, vol. xxii. 



