PUS. 147 



Again, the microscope will frequently determine the nature 

 of a suspected fluid, by indicating in it the existence of 

 shreds of cellular tissue, muscular fibrillse, and a variety of 

 other organisms which enter into the formation of the human 

 body ; and by the presence of one or more of which, not merely 

 the nature of the puriform matter may be ascertained, but 

 also the locality from which the pus had itself proceeded. 



DETECTION OF PUS IN THE BLOOD. 



From what has been said in reference to the structural 

 identity of the white corpuscle of the blood with that of 

 mucus and pus, we are prepared for the announcement that 

 no known characters exist whereby the presence of pus in the 

 blood may be established by the microscopic examination of 

 that fluid. 



That the elements of pus in some cases are really present 

 in the blood, circulating with it, scarcely admits of a single 

 doubt, since it is not unfrequently met with in situations, such 

 as on the lining membranes of the vessels, where it is utterly 

 impossible for it to remain without some portion of it be- 

 coming commingled with the blood. 



The same fact is also proved by the spontaneous absorp- 

 tion of large collections of matter, an occurrence which is not 

 unfrequently witnessed, and which is only to be accounted for 

 on the assumption that the elements of pus are again absorbed 

 into the blood from which originally they were derived. 



There can scarcely be a question, then, that pus is occa- 

 sionally contained in the living blood, although we possess 

 only indirect means of establishing this fact ; and according 

 to the views here entertained, it may be present in the blood 

 in two ways : thus, as we have seen, it may be formed in the 

 blood-vessels themselves, or it may be formed without those 

 vessels, and again reabsorbed into the blood from which in 

 every case it almost immediately proceeds. 



But pus, as we know, is composed of two elements, the one 

 fluid, the other solid, the globules. Now we must not expect 

 t<> >rc pus circulating in the blood as pus, although that 



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