PUS. 153 



But, conversely, if we add an extremely dilute mineral acid to 

 pus which has been mixed with such a saline solution, it rarely 

 happens that we can again render the nucleus visible. On this 

 account we can rarely detect the presence of nuclei in the cytoid 

 corpuscles of the urine in catarrh of the bladder by means of a 

 dilute acid. 



An aqueous solution of iodine (1 part of iodine in 9,000 parts 

 of water), containing a trace of hydriodic acid, does not coagulate 

 the serum of the pus, but it imparts a yellow colour to the 

 corpuscles, causes them to swell, and brings the nuclei more 

 prominently into view. A concentrated solution of iodine (whether 

 the concentration be effected by chloride of sodium, spirit, or 

 hydriodic acid) coagulates the serum of the pus, and brings into 

 view the nuclei of the corpuscles which are not entirely concealed 

 by the coagulated albumen. 



Whatever evidence these micro-chemical experiments may 

 afford on the question of endosmosis, they throw very little light 

 on the internal chemical nature of the pus- corpuscles, and scarcely 

 even indicate the direction we ought to follow in rendering the 

 separate morphological constituents of the cytoid corpuscles 

 accessible to more exact chemical inquiry. This much only 

 seems clearly established, namely, that the investing membrane, 

 the viscid contents, and the nuclei, are substances very closely 

 allied to albumen; nearly all of them exhibiting the reactions 

 peculiar to the protein-bodies. The investing membrane is a 

 protein-body, which does not merely swell in a gelatinous manner 

 in very dilute acids, but actually dissolves in these fluids. This 

 property, which it exhibits in common with albumen and muscle- 

 fibrin, distinguishes it very decidedly from blood-fibrin, which 

 swells up, but does not dissolve in dilute hydrochloric acid. This 

 membrane is wholly insoluble in alkaline salts, and does not dis- 

 solve readily even in the caustic alkalies. These properties very 

 strongly exhibit the points which mainly distinguish it from 

 neutral albumen which is poor in salts (such, for instance, as the 

 albumen obtained from an alkaline solution by neutralisation with 

 acetic acid and by excessive dilution, or by the careful addition of 

 dilute spirit,) or from casein which has been freed from salt and 

 acid (according to Bopp's mode of exhibition), whilst its behaviour 

 towards the caustic alkalies and their carbonates and borates 

 makes it approximate more nearly to muscle-fibrin (syntonin). 

 If the serum of the pus and the viscid contents of the corpuscles 

 admitted of being removed, the most practicable method would 



