BACTERIUM SYNCYANEUM. 291 



Agar Stab. — Just like that in gelatin. Usually the 

 surface growth is a little more luxuriant (27, iv). Com- 

 pare 27, i-iii. 



Agar Streak. — ^Moist, usually grayish-white growth, 

 with a smooth, wavy border. Water of condensation 

 cloudy, with a grayish- white sediment. The agar presents 

 most variable colors. Sometimes cultures can not be dis- 

 tinguished from those of the Bact. putidum. 



Bouillon Culture. — Moderately cloudy, at first gray- 

 ish-green, later with many cultures, becoming blue to 

 bluish-green. Precipitate moderate, whitish-gray, feebly 

 coherent. Pellicle formation is observed in some cases, 

 and not in others (27, v). 



Milk Culture. — Bluish-green color; otherwise unaltered. 

 Reaction alkaline (27, vi). "With the addition of hydro- 

 chloric acid the color becomes blue, if a culture is employed 

 which forms syncyanin. Upon unsterilized milk the color 

 is deep to sky blue on account of the acid produced by the 

 Bact. acid, lactici. 



We obtained beautiful blue milk by adding 1 % grape- 

 sugar to sterilized milk or, better, whey ; grape-sugar, 

 particularly, is converted into acid by Bact. syncyaneum. 



Potato Culture. — According to the variety of potato, 

 growths resulting from inoculation with the same culture 

 may vary widely. The growth is greenish or brownish-bJue, 

 blackish-blue, dark brown, yellowish-brown, or gray, 

 always glistening, sometimes a little elevated. The potato 

 is discolored greenish, brown, gray, blue, etc. (28, i-iii). 

 In many cases it can not be distinguished from Bact. 

 fluorescens, especially if the formation of l}Iue pigment is 

 slight or absent. 



Other Nutrient Media. — Grows and produces pigment 

 upon non-albuminous nutrient media. As pointed out by 

 Hiippe, tartrate of ammonium serves as the source of car- 

 bon and nitrogen. 



Resistant Properties. — Against drying, five to seven 

 months (Heim). Spores are certainly not present (Heim). 



Chemical Activities. — Chromogenesis : Most cultures 

 form two pigments, the fluorescent yellowish-green bac- 

 teriofluorescein, and also the blue syncyanin. We have 

 possessed cultures which no longer produced any trace of 



