THE BIOLOGY OF MICROBES, ETC. 139 



Bacterium xantMnum. This bacterium is the 

 cause of 'yellow milk/ which at first is acid, but 

 soon becomes alkaline. The pigment produced by 

 this bacterium is soluble in water, and insoluble in 

 alcohol and ether. B. xanthinum measures from 

 07 to I'O ft in length, and forms colonies on pota- 

 toes. 



Bacterium septicus agrigenum. This microbe 

 occurs in soils, and measures from 2 to 3 /z, in length. 

 On plate cultivations it produces colonies of a greyish- 

 yellow colour, with a yellowish-brown centre. This 

 microbe is fatal to mice, rabbits, and guinea-pigs. 

 It multiplies rapidly in the blood, and it adheres to 

 the red blood corpuscles. 



Bacteriumcoli commune. This bacterium measures 

 1-7 fi in length and 0'4 p in breadth, and it occurs 

 in the faeces of infants fed on human milk. It 

 grows on nutrient gelatine, forming granular colonies 

 of a yellowish colour. It is fatal to rabbits and 

 guinea-pigs, causing violent diarrhoea and fever. 



Bacterium fcetidum. This microbe was discovered 

 by Dr. Thin 1 in the alkaline serous exudation from 

 the soles of the feet of a person who suffered from 

 profuse sweating of the feet. It produces a foetid 

 odour, which is also observable in artificial cultures 

 of this microbe. B. fcetidum occurs singly, in pairs, 

 and leptothrix threads. This microbe appears to be 

 identical with Rosenbach's Bacillus saprogenes ; and 

 it is readily cultivated in agar-agar and blood- 

 serum. 



Bacterium Neapolitanum. This microbe occurs as 



1 Proceedings of Royal Society, vol. xxx. p. 473. 



