Lord Lister. 



xix 



that they were not like dead inert tissues, ready to become the home of 

 organisms if only the latter gained access to them. He further came to the 

 conclusion that these various septic diseases must be due to different forms 

 of organisms, and some years after the commencement of his work, he with 

 great diffidence promulgated the idea that tetanus, which at that time was 

 looked on as a disease of the nervous system, was really nothing more than 

 an infective disease of wounds, a view which was laughed to scorn by his 

 contemporaries. It is remarkable how many of the views which he was 

 constantly expressing to his intimates, and indeed to his students, have been 

 verified by the progress of bacteriological work. 



Apart from bacteriological work directly bearing on the best methods 

 of excluding bacteria from wounds, Lister made several bacteriological 

 researches in other directions. He made mauy experiments on spontaneous 

 generation to test the accuracy of the previous results, and also extensive 

 observations on the germ theory of fermentative changes. At the beginning 

 of his work, he spoke of bacteria in connection with wounds as if they were 

 all the same, but very soon he saw that there must be many different kinds 

 of bacteria, each with their own special effect on the medium in which they 

 grew. He was the first to demonstrate this point in his beautiful research 

 on " Lactic fermentation," published in 1877, in which he showed that this 

 change in milk was due to a particular organism which he called the 

 Bacillus lactis, and which he was able to isolate by a very ingenious method 

 from the many other forms of organisms which are present in milk. 



In the course of his work on the best antiseptic materials for dressings 

 (which he usually tested by packing them loosely in a tube, saturating them 

 with fresh blood and then inoculating the blood at one end of the tube with 

 putrefying material) he. made the remarkable observation that a definite 

 quantity of the putrid material must be inoculated in order to start the 

 putrefactive process in blood, and that if the quantity was too minute, even 

 though it contained a number of bacteria, putrefactive changes might not 

 occur, indeed the organisms would not grow. The writer does not remember 

 if this observation was ever published ; it may have been mentioned in some 

 of his papers, but it led the author to investigate whether anything of the 

 kind occurred in infective diseases in the living body. These researches 

 showed that a similar condition prevails in infective diseases, and that 

 the occurrence and the virulence of the infection in individuals not 

 extremely susceptible to the disease depend to a very large extent on the 

 dose of the infective material in the first instance, a fundamental and very 

 important point in the natural history of these affections. 



In addition to his antiseptic and scientific work, Lister wrote several 

 papers on surgical subjects which were characterised by the same care and 

 thought as were his other works. Of these, his articles on "Amputations" 

 and " Anaesthetics " published in Holmes's ' System of Surgery,' and his paper 

 on " Excision of the Wrist," may be specially mentioned. These articles 

 alone would suffice to stamp him as a good practical surgeon. 



