X PREFACE 



new; some of the details have already been published 

 in the scientific journals, but the greater part of what is 

 herein set forth has hitherto been unknown. The new 

 methods have revealed many interesting facts which in 

 my opinion may be far-reaching in their influence in 

 the advancement of pathology. 



It may not be out of place if I give a brief history 

 of the circumstances which led to the adoption of this 

 in-vitro method of microscopical investigation and of 

 the researches which have been made by means of it. 

 There can be no doubt that accidents have on more 

 than one occasion been responsible for valuable indica- 

 tions which have led to fruitful lines of work, and had 

 it not been for some of these accidents the results 

 attained would have been considerably less advanced 

 than they are now. I do not think that these re- 

 searches would have been started at all had it not been 

 for the firing of a gun. In the summer of 1905, when 

 I was a surgeon in the navy, my cabin being my 

 laboratory, I was interested in bacteriology, and 

 was endeavouring to grow organisms from the blood 

 of patients. To do this I had to invent an electric 

 incubator, it being impossible on board a battle- 

 ship to use one which was heated either by gas or oil, 

 the former not being available and the latter not 

 allowed. There was nothing for it, therefore, but to 

 invent an incubator which could be made on board, 

 and I look back upon this piece of apparatus with 

 interest. It was not so reliable as those which can 

 now be bought, but it worked fairly well. It had an 

 automatic thermostat, by means of which the lamp was 



