slightly serrate, later spreading and red with green iridescence. 

 On slant agar and potato, pigment production usually poor, 

 growth luxuriant but dirty white. Unlike any other of the red 

 forms, B. ruber indicus produces pigment more readily on al- 

 kaline than on acid or neutral agar (cf. section on special media). 

 Bouillon, pellicle and sediment usually white, but in a peptone 

 and water solution vivid red pigment is formed. Milk, coagulum 

 completely peptonized in 10 days at 37 C. Gas, all C0 2 , is 

 formed from sucrose as well as from dextrose bouillon, but none 

 from lactose. Development with pigment takes place at 37 C. 

 Nitrate, reduced to nitrite and further to free nitrogen or 

 ammonia. Odor, not characteristic. 



B. plymouth ensis (Fischer, 54). 



Isolated from water and described by Fischer (1887). The 

 complete description is as follows: (Ein) "beweglich(er) Bacillus, 

 den ich in der Wasserleitung von Plymouth entnommenem Trink- 

 wasser fand und der sich nicht nur durch seine Gestalt (kleine, 

 dicke Stabchen mit abgerundeten Enden, kurze Faden bildend), 

 sowie durch die karmoisinrote Farbe des Pigments von den bisher 

 bekannten, einen roten Farbstoff bildenden Bakterien (Micro - 

 coccus prodigiosus, Bacillus ruber indicus Koch, und 

 Bacillus ruber Frank) unterscheidet, sondern auch durch eine 

 stark fadenziehende Beschaffenheit der Kulturen , sowie durch leb- 

 hafte Gasproduktion gut charakterisiert ist." Voges (55) (1893) 

 also made some observations on this form, which my results con- 

 firm and amplify. 



The pigment formed by B. plymouthensis on ordinary 

 media could be distinguished from that of B. prodigiosus only 

 by its less vivid color and tendency to deteriorate into a violet 

 pink. Freshly rejuvenated cultures sometimes showed metallic 

 luster on agar, but, contrary to V o g e s' observations, not on potato. 

 The "fadenziehende" character, mentioned above, seemed constant 

 in B. plymouthensis I during two years' observation , after 

 which it disappeared. This character also appeared in a culture of 

 B. prodigiosus I, and is present in B. prodigiosus VIII 

 (cf. section on discontinuous variation). The main points of distinc- 

 tion between the Prodigiosus type and B. plymouthensis 

 are (1) slower liquefaction of gelatin beginning with a cupshaped 

 depression (cf. B. prod. V), (2) a vigorous (contrary to Voges) pro- 

 duction of gas, 7078 % of it C0 2 , in dextrose, lactose and suc- 

 rose bouillon. Gas, 42 % of it C0 2 , is also formed in a standard 

 asparagin sugar solution. Cultures ofB. plymouthensis I have 

 a strong fecal odor. 



B. kiliensis (Breunig), B. ruber balticus (Kruse). 



Isolated from water and described by Breunig (56) (1888). 

 A culture from Krai under the name B. ruber balticus corre- 

 sponds to the description of Breunig and to that of Laurent 

 (57), who worked on the variability of the "Bacille rouge de Kiel". 



