1912.] 



The Electrical Conductivity of Bacteria. 



335 



medium is mentioned because of the great difference between cultures on or 

 in different media, in the case of B. typhosus, for example. 

 The chief points established by the values found here are : — 



(1) The electrical conductivity of any organism is not independent of the 

 culture medium used. 



(2) Bacteria which have their habitat in the animal have higher con- 

 ductivities than those usually found external to it. 



(3) The former have, on the whole, a higher conductivity than blood. 



Table I. — Specific Eesistances of Bacteria. 



Ohms per 



1. coli communis 



„ from fresh sewage 



?. typhosus 



?. euleritidis sporogenes 



ewage streptococcus 



''rotcus vulgaris 



?. violaceus 



'licrococcHS prodigiosus 



?. subtilis 



?. anfhracis 



1. acidi lactici 



Agar, rather dry. 

 Agar, moist. 

 Broth. 



Agar, from broth. 



„ from agar. 

 G-elatine, from broth. 

 Agar. 



Boiled 1 hour, 200 ohms before boiling. 



Autoclaved 5 hrs., „ 



Agar. 



In order to see how this variation depended upon the resistances of the 

 media themselves, the following measurements were made : — 



Table II. — Specific Eesistances of Culture Media, Milk, and Water 





Ohms per 

 cm. cube. 







60—70 







115 







275 







290 





Broth 



70—104 



No two samples from different stocks the 



Blood serum 



96 



Separated by standing. 





200 







. 245 





