154 



a fresh-laid egg perfectls^ hard : we will then put two 

 small portions of the yelk, slightl}^ moistened with 

 sterilized water, each into a Petrie dish. After two or 

 even one minute's exposure to the air we will place 

 the covers on the dishes and put them away, one into 

 an incubator at a temperature of loo'^ F. and the 

 other into a cupboard at the ordinary temperature of 

 the air, say about 60^^ F. Going back to the egg we 

 will make a slide preparation from it, staining with 



Gentian Violet. This on examination under a — in. 



12 



oil-immersion lense will be found to be quite free 

 from any micro-organism, thus shewing that at the 

 beginning of the short exposure to air the portions 

 in the Petrie dishes were also free from any 

 contamination. 



If when twenty-four hours have elapsed we make 

 a film of the egg which has been incubated at 100*^ F. 

 staining as before with one of the microscopic dyes 

 (Gentian-Violet b}^ preference) in order to throw into 

 prominence any microbes that may be present, we 

 shall find it to l)e a teeming mass of septic cocci and 

 bacilli, derived from its inoculation during the brief 

 period of a minute with the septic spores contained 

 in the air. The same condition will be found in the 

 specimen at 60° F., but in this case we shall have to 

 wait for three or four days to have gone by, thereb}" 

 learning that while 3^elk of egg is always a particularly 

 good medium for the cultivation of the septic bacillus 

 its fostering .qualities are considerably influenced by 

 the temperature at which it is kept, and that heat 

 greatly enhances the vigorous growth and develop- 

 ment of the bacillus. As a natural corollary to this 

 will follow the deduction that the more vigorous are 

 the bacilli, in consequence of the heat associated 

 with their generation, the more virulent will be their 

 nature and the more able will they be to work harm 

 when they are placed in a position, where from being 



