48 MICRO-ORGANISMS AND DISEASE [CHAP. 



Now, having filled the required number of test-tubes and 

 flasks with the required quantity of fluid, I subject these 

 seriatim to boiUng. By means of an ordinary test-tube 



^-f^^T- ^^^^ 



Fig. 



-A Beaker containing a Number of Culture-tubes Plugged 

 WITH Cotton-wool. 



holder I hold them above a very small flame until the fluid 

 boils, and keep it so boihng for from half to one minute. 

 During this process of boiUng the cotton-wool is only slightly 

 pulled up, and immediately before ceasing to boil the plug 



