334 AN ADDRESS ON 



leucocytes in inflammation would prove to have so far-reaching a bearing upon 

 the pathology of infective diseases ! 



I have brought before you two samples of the kind of evidence upon which 

 the phagocyte theor}^ rests, and if we accept it, as I believe we must, it serves at 

 once to explain much that has hitherto been mysterious in the relations of micro- 

 organisms to wounds. Take, for example, that which the surgeon makes for the 

 cure of hare-lip. Its posterior edge is perpetually bathed with the saliva, which 

 contains many kinds of septic bacteria. But these do not enter and people the 

 fibrine that glues together the cut surfaces, as they infallibty would do if those 

 surfaces were composed of glass or any other chemically inert material destitute 

 of life. It has long been very evident that the living tissues exerted a potent 

 influence in checking bacteric development in such a wound ; but what was the 

 nature of that influence ? This used to be an enigma, but now receives its 

 natural explanation in the phagocytic action of the cells that crowd the lymph 

 soon after its effusion. 



At the London Congress I brought forward an experiment which proved 

 that a blood-clot within the body may exert a powerful anti-bacteric agency. 

 I will not repeat the details of that experiment further than to say that a very 

 small piece of linen cloth soaked with putrid blood was mounted by means of 

 silver wire in the interior of a short glass tube open at both ends, which was 

 slipped into the jugular vein of a donkey, and kept in position between two liga- 

 tures. After two days the venous compartment was removed, and the coagulum 

 within it investigated. In and near the glass tube it was in a state of advanced 

 Dutrefaction, as was indicated by its foul odour and greatly altered appearance ; 

 and microscopic examination showed that it abounded with bacteria. But near 

 the wall of the vein it looked to the naked eye like a recent clot ; I could not detect 

 in it any putrid odour, nor could I discover bacteria with the microscope.^ Stained 

 sections of these outer parts of the coagulum, made after hardening in alcohol, 

 showed great multitudes of cells differing from one another in size and other 

 characters, just as is often the case with Metchnikoff's phagocytes. I supposed 

 that these cells must have been in some way or other the anti-bacteric agents, 

 but how, I could not imagine. The phagocyte theory clears up the mystery. 



By means of this same theory we can account for what would otherwise 

 have seemed to me incomprehensible — the use, without evil consequences, of 

 silk ligatures which have not been subjected to any antiseptic preparation. We 

 learn from the experiments of Ziegler and others that leucocytes soon penetrate 

 very thin spaces between plates of glass or other chemically inert foreign bodies 

 inserted among the tissues. And we can understand that they may creep into 



* See Transactions of the London International Medical Congress (p. 275 of this volume). 



