Vi] GENERAL CHARACTERS OF BACTERIA 



99 



Observations were made on the common staphylococcus 

 pyogenes aureus, the bacillus of swine fever, the bacillus of 

 grouse disease, the bacillus of fowl enteritis, and the bacillus 

 of diphtheria, as to the amount . of multiplication these 

 several microbes undergo when a definite number of them 

 is introduced into faintly alkaline beef broth (eight to ten 

 cubic centimetres), and kept in the incubator at about 

 37° C. All these different organisms grow with great 

 rapidity, and after twenty-four hours the broth is uniformly 

 turbid, provided the number introduced at starting be com- 

 paratively large. By making gelatine plate-cultivations with 

 . a given small quantity of the broth previously diluted to a 

 definite degree, and then counting the number of colonies 

 that make their appearance on incubation, it is easy to 

 calculate the number of microbes present per cubic centi- 

 metre in the broth. In some experiments made with the 

 staphylococcus pyogenes aureus it was found that on intro- 

 ducing 248 microbes per cubic centimetre, they increased 

 in the first twenty-four hours to 20,000,000 per cubic centi- 

 metre ; in another experiment 640,000 per cubic centimetre 

 were counted after the first twenty-four hours' growth, 

 248,000,000 per cubic centimetre after the second twenty- 

 four hours — i.e. after forty-eight hours' incubation, and 

 1,184,000,000 per cubic centimetre after the third twenty- 

 four hours — i.e. after seventy-two hours' incubation. From 

 a number of experiments it was calculated that for each 

 microbe introduced, the multiplication during the first 

 twenty-four hours is 80,000-fold, during the second twenty- 

 four hours 400-fold, and during the third twenty-four hours 

 5-fold. 



The rapidity of the growth and multiplication of the 

 bacillus of fowl cholera in the living blood was ascertained 

 in an experiment made on a rabbit. Of the microbes 



H 2 



