142 ORGANISED FLUIDS. 



between the fluids in which a distinction has been sought 

 no microscopic difference exists. The inquiry has been made 

 on the false assumption that mucus and pus are really essen- 

 tially distinct ; and its importance has been magnified by the 

 idea that it would impart, as indeed it undoubtedly would do 

 if real, increased assistance in the diagnosis of disease. 



Since, however, the establishment of the fact that pus may 

 be formed independently of any appreciable structural lesion, 

 much of the interest which was supposed to attach to this 

 inquiry has been lost, and that which still appertains to it 

 has been further lessened by the demonstration at which 

 we have arrived, by means of the microscope, of the perfect 

 identity of pus and mucous corpuscles. 



Now the manifestation of this identity by the microscope 

 is not less a triumph of that instrument than if it had really 

 proved that the notion of physiologists was actually founded 

 on fact, and that there does really exist a tangible difference 

 in the microscopic characters of the two fluids. 



Notwithstanding the absence of any positive known mi- 

 croscopic character, whereby at all times, and in all conditions, 

 pus may be discriminated from mucus, this want of know- 

 ledge, arising from the very sufficient fact to which allusion 

 has already been made, viz. that no such character really 

 exists, the two fluids under discussion may frequently be 

 distinguished, at a glance, by certain outward and physical 

 properties and appearances, and this is especially the case 

 when they occur without admixture with each other. 



These differences in the outward character of the two 

 fluids are not always, however, equal to their discrimination, 

 and which arises from the fact, that they are all of them 

 subject to the greatest possible variation, so that there is not 

 one which can be regarded as truly distinctive. Thus in 

 morbid conditions, the one fluid will pass by insensible 

 degrees into the other, or they will both be mingled together 

 in such proportions as to set at defiance all physical means 

 employed to distinguish them. 



But it may be said that the chymist can at all times dis- 

 tinguish pus from mucus : there can be no doubt but that, 



