386 Sir Rickman John Godlee [March 12, 



with Hfe and definite individual functions. Some of them are appar- 

 ently essential to the success of our bodies as a going concern. 

 Many, even of these, are only waiting for some interference with the 

 vitality of a part, or the whole, of our l)ody, to afflict us with local 

 or general disease, and finally to dissolve us into our elements. 



Metchnikoff showed how these mahgnant organisms are kept at 

 bay. Our very own body is made up of cells, each of which has, so 

 to say, its individual existence and its special functions — almost its 

 special intelligence— a fact which Lister was one of the first to 

 demonstrate, .Hosts of these cells — Metchnii^off's phagocytes — form, 

 some of them, our main mobile army of defence. They are not like 

 other defensive cells, such as those of the spleen and bone marrow, 

 confined to their fortresses, though as a rule they keep their allotted 

 positions. But they can move along strategic railways to any special 

 point of attack, and when they have reached it, there ensues a l^attle 

 royal with the invading army of pathogenic organisms, which they try 

 to swallow, and, if possible, to destroy. If they are successful, 

 health is restored. It may mean the aborting of a cold in the head, 

 the subsidence of a pneumonia, or the rapid healing of a cut. If, on 

 the other hand, they are overpowered by the invaders, the catarrh 

 may extend to the smallest bronchi, the pneumonia may end fatally, 

 or the wound may suppurate with disastrous results. 



These illuminating facts turned the attention of surgeons into 

 another direction ; and seeing that everyone knew that the vitality of 

 phagocytes must be impaired by any mechanical or chemical injury, 

 the tendency was to reduce the strength of the antiseptics and to 

 trust more and more to the phagocytes. Lister himself used weaker 

 and weaker antiseptic lotions, but he never thought it wise to dispense 

 with them altogether. Others, however, being chiefly obsessed with 

 the notion that chemical antiseptics diminish the power of the phago- 

 cytes, maintained that their use should be altogether discontinued, and 

 have adopted, or say they have adopted, a treatment which, though 

 having the same object as Lister's, is supposed to be founded upon a 

 different principle. How far this is actually the case it will presently 

 be our business to inquire. 



This was one of the reasons why it began to be said that Lister's 

 teaching, like the Old Testament, was obsolete, and must be replaced 

 by a newer and more perfect gospel. 



We must now further consider hoAV far the air is really a source 

 of infection. In the early days it was said that the number of germs 

 in the air was enormous. As a matter of fact, such a statement is 

 still true, as is easily shown by exposing a plate of cultivating 

 medium in any room, say in the most up-to-date modern operating 

 theatre. 



It was also taken for granted that the large majority of germs 

 were pathogenic — that is, disease-producing. But very little was 

 known, in 1865, of the varieties of micro-organisms. It is true that 



