T^'/l BEHAVIOUR OF r.ACTEKJA. 



tion of milk complete within a week. Stratiform liquefaction of 

 p^elatine stab complete in five days at 22 degrees (,". yVgar stab 

 uncharacteristic, thick, and spreading on the surface, filiform 

 below. Growth on potato good, more opaque, viscid, and of orange 

 colour. Growth in bouillon rapid, viscid, with incoherent surface 

 film, and thick slimy sediment. Indol production marked. 

 Cheesy faecal odour marked, but not very characteristic. 



Five different non-si)orulating organisms, highly tolerant of 

 arsenite, were isolated from the dipping tank or from cattle faeces, 

 in addition to B. arsenrediiccns and B. fluorcsccns alread} men- 

 tioned, ihese are similar in biochemical characteristics, and are 

 of frequent occurrence in arsenical dips. They grow readily in 

 media containing 0.8 per cent, to 1.2 j^er cent. AS2O3 as sodium 

 arsenite, and tolerate still higher concentrations of arsenate, but 

 neither oxidise arsenite nor reduce arsenate. Three of them 

 have the same group number in the classification system of the 

 Society of American Bacteriologists, but are morphologically 

 different. References to rate of growth mean growth at 2'!^ 

 degrees C.* 



a. 212.3332033. Actively motile rods generally .4/a X i-5/^, 

 but varying if rom i^t to 3/u, in length. Lojx>trichic. usually with 

 four flagella. Marked tendency to long chain formation. Gram 

 negative. Stains easily with ordinar\^ dyes, usually in bipolar 

 fashion. (Growth fairly rapid, colonies reaching 2 mm. in three 

 days, raised, translucent, shiny, with crenate edges and granular 

 interior. Growth on agar slope good in three days, translucent, 

 and slightly beaded at first ; later flat, smooth, more ojjaque, 

 butyrous, but easily detached with a needle. Agar and gelatine 

 stabs uncharacteristic, filiform, with good, but rather thin sur- 

 face growth. Turbidity in bouillon in 24 hotu's, with fairly 

 abundant, easily dispersed sediment in three days. No Indol 

 production. Odour uncharacteristic. On potato growth is slow, 

 scanty, and uncharacteristic. Litmus milk goes slightly alkaline, 

 but is otherwise unchanged. Sugar bouillon goes slowly alkaline. 

 Grows freely in arsenite bouillon to 0.8 per cent. As'20.j, ])tit 

 inhibited by concentrations above i per cent. 



p. 213.3332033. Non-motile organism of cocco-bacterial 

 habit; dominant form a slightly oval coccus .8/i, X -6/*, especially 

 in arsenite bouillon. In ordinary bouillon, and sometimes on 

 agar slopes, may show rod forms up to 2^t in length. Weakly 

 Gram-positive. In general growth characters not unlike a, but 

 with colonies slightly umbonate and with entire edges. Potato 

 growth abundant, flat, and greyish white. Gelatine stab not 

 characteristic ; filiform — echinulate with a fairly dense surface 

 disc. Litmus milk goes alkaline from the surface downwarrls 

 and the litmus is bleached from below ; otherwise unchanged. 

 Grows freely in arsenite bouillon \\\) to concentrations of 1 per 

 cent. As.jOg. 



* The group numbers indicate the major characteristics — sporuIati(.j!i, 

 oxvi^en requirements, colour, action on gelatine, sugars, nitrate, etc. 



