As the said authors had not applied in their experiments the so intense colouring 

 of ferrisalts by protocatechetic acid, it seemed desirable to make use of it for the 

 easier recognition of the inferred bacteria. 



To this end the experiment was effected as follows: 



For the rough or preliminary cultivation a liquid was used of the composition: 



Tapwater 100.00 



Dikaliumphosphate 0.05 



Ammoniumchlorid 0.05 



Calciumchinate (C 7 HnO 6 )2 Ca + ioH 2 O o.i to 10 

 Ferrichlorid o.oi 



In a wide Erlenmeyer flask, so that a strong aeration occurs in the thin 

 layer, inoculated with soil and cultivated at 20 to 25 or 30 to 35 C., the liquid 

 colours deep black after a few days, in consequence of the formation of ferriproto- 

 catechate. 



To purify the bacterial culture a trace is transferred to a similar medium and 

 cultivated at 20 or 30 C. 



If this culture is sown on a medium of the same composition but solidified with 

 agar and containing some ferricitrate 1 ), colonies are obtained, from the cultures 

 kept at 20 to 25 C., of different varieties of B. Huorescens, and from those kept 

 at 30 to 35 C. chiefly of a Micrococcus, all lying amid diffusion fields of ferriproto- 

 catechate of an intense violet or red colour. This Micrococcus belongs perhaps to 

 the same species as that described by E m m e r 1 i n g and Abderhalden, but 

 then certainly to another variety, for it does not produce, neither in presence of 

 peptone nor of ammoniumsalt. This form, very common in our environment and 

 which can be obtained with various other organic salts in a similar way as with 

 chinate, I shall name Micrococcus calco-aceticus, as calcium acetate is very fit for 

 its accumulation. Here it may be observed that acetates are also very useful for the 

 accumulation of certain varieties of B. fluorescens non-liquefaciens which still grow 

 at 30 C. 



Streaks of these various bacteria on broth agar with one proc. calcium chinate, 

 and a little ferricitrate, or on the above medium, give again deep black or red- 

 coloured diffusion fields of ferriprotocatechate. 



Part of the chinate oxidises directly to water and calciumcarbonate which preci- 

 pitates as crystals dyed deeply violet, by having sucked up the ferrisalt of the proto- 

 catechetic acid during their crystallisation. 



Other species, able to convert the chinic acid into water and calciumcarbonate 

 or protocatechetic acid, but not found in the foregoing experiments, are mentioned 

 in the following table where it is indicated by + and - - whether the substances placed 

 at the head are either or not formed. These experiments were made with broth agar- 

 plates with i proc. calciumchinate at 30 C., or use was made of the above named 

 nutrient liquid containing ammonium chlorid, after its solidification with agar. 



') Ferricitrate does not give a precipitate of ferriphosphate in the somewhat al- 

 kaline broth. 



