PREFACE XI 



switched out at a given temperature, and was switched 

 on again when the temperature fell. Sparking gave 

 trouble, but I "blew out" the spark by a condenser. 

 It w r as made by a "torpedo instructor," and was so 

 firmly bolted on to the steel bulkhead in my cabin that 

 apparently nothing would (or could) shake it down. 



One afternoon, when my ship was in the Mediter- 

 ranean, we had, as I thought, finished heavy gun-firing. 

 I had placed some blood on to some nutrient agar 

 (sloped) in culture-tubes, which were in my incubator, 

 being kept at the blood temperature of 37 C. I was 

 working at the cabin table with the microscope and my 

 small stock of bacteriological apparatus. Suddenly, 

 without any warning, a "young gentleman" fired a 

 12-inch gun from the after-babette on the deck above; 

 for the captain had permitted the midshipmen to fire 

 a "round" after the main gunnery practice was over. 

 I extricated myself from the debris of microscope, 

 apparatus, pictures, etc., on the deck of my cabin, for 

 nearly everything was smashed. My incubator, firmly 

 fixed, as I have explained, on to the bulkhead, I did not 

 open, expecting that everything inside was shattered, 

 and it was not until the next day that I investigated its 

 contents. My surprise may be imagined when I found 

 that the culture-tubes were unharmed, but that, owing- 

 to the dislocation of the automatic thermostat, the 

 temperature inside the apparatus w r as standing at 60 6 C. 

 On close examination of the culture-tubes, I noticed 

 that the red cells, which had been resting on the surface 

 of the jelly, were now diffusing as a cloud through the 

 jelly itself. The matter w r as further investigated, and it 



