140 EXUDATIONS. 



has been digested for a short time in a dilute solution of nitre 

 becomes dissolved and is coagulable or precipitable by acetic acid. 

 (The washing is, however, by no means easy and frequently entirely 

 fails, since the turbid fluid passing through the filter very soon 

 closes its pores.) This insoluble residue swells up in a gelatinous 

 form in very dilute hydrochloric acid ; but some portion is 

 actually dissolved, without, however, yielding the reactions of 

 ordinary muscle-fibrin. A microscopical examination shows that 

 the constituents of the very numerous cells contained in aphthous 

 exudations are dissolved by water containing hydrochloric acid. 

 Rokitansky's croupous exudation a, or fibrin ft, contains true 

 fibrin, in addition to the granular matter and the first stages of 

 cell-formations; but although it is not very rich in blood-cor- 

 puscles, it is never entirely free from them. After an exudation of 

 this kind has been comminuted and carefully washed with distilled 

 water, and then immersed in a solution of nitre of the previously 

 named concentration, at a temperature of 30 or 40, a great por- 

 tion of it is always dissolved, whilst the fluid is also found to con- 

 tain a protein-substance, which is precipitable by heat at the 

 boiling point, as well as by acetic acid; and here I must not omit 

 to mention, that with the exception of two cases, T never found 

 the so-called arterial fibrin (which is perfectly insoluble after diges- 

 tion in a dilute solution of nitre), even in those exudations which 

 according to microscopical examination appeared to contain true 

 fibrin. The croupous exudation a, after being previously well 

 washed in water, swells in dilute acetic acid ; but a very small 

 amount of the protein -substances, especially such as are recog- 

 nisable by chromate of potash, are dissolved. Rokitansky drew 

 attention to the large amount of fat contained in these exudations, 

 and the fact may be readily confirmed by careful chemical analysis. 

 The fat does not differ essentially from that of fibrin ; but the fat 

 containing phosphorus or rather the phosphate of glycerine appears 

 to be present in rather larger quantities in the croupous exudation a 

 than in exudation ft or in the aphthous kind ; but it must be admit- 

 ted that there exists considerable uncertainty as to the quantitative 

 determination of these substances. This observation seems to be 

 confirmed by the fact, that these exudations on an average leave 

 more earthy phosphates, and in general more acid phosphates, on 

 the incineration of the constituents insoluble in water, than the 

 ordinary blood-fibrin. I never found less than 2-g-, and often more 

 than 4-J- of phosphates in the insoluble residue of the exudation. 

 Notwithstanding my conviction of the insufficiency of elementary 



