88 FRED W. TANNER 



and probably secured "the pyocyanin" of Fordos (1863). This 

 was blue in alkaline and red in acid solution, and crystallized in 

 rhombic crystals. A red-brown substance was also secured 

 which was greenish in refracted light, soluble in water and 

 insoluble in chloroform. In acid solution fluorescence was lost, 

 but was acquired again in alkaline solution. By distillation a 

 colorless substance with a peculiar odor was obtained. This 

 differed from the original and was supposed to be a decomposi- 

 tion product. 



Thumm (1905) found that all species produced the same pig- 

 ment, which differs from the reports of other investigators. He 

 was unable to confirm the findings of others that several pig- 

 ments were produced. He found that this group was made up 

 of vigorous alkali formers, and that glucose was fermented to 

 acids which were neutralized later by the formation of ammonia. 



Boland (1899) believes that two pigments are formed, a fluo- 

 rescent one, which is formed by many other bacteria, and pyo- 

 cyanin which changes into a red brown pigment by oxidation. 



Krause (1900) studied the symbiosis of B. pyocyaneus with 

 pus formers and found that the aromatic odor was almost always 

 present, and that as long as B. pyocyaneus predominated over 

 the pus formers, the green color did not appear. When B. 

 pyocyaneus cells were removed from the culture, they again 

 formed the green pigment. Certain gases were tried, and with 

 hydrogen good growth was secured but no pigment. With 

 CO2 and the vacuum method no growth was secured. In his 

 study of the pigments the following were secured: 



(1) Water extract, greenish yellow fluorescence; (2) 80 per 

 cent alcohol, yellowish green fluorescence; (3) glycerol, blue- 

 green fluorescence; (4) Amyl alcohol, grass green fluorescence; 

 (5) chloroform, blue; (6) ether, yellow blue. 



Nogier, Dufourt and Dujol (1913) studied a strain from a 

 lesion and found a red pigment of the color of vinegar along with 

 the fluorescent and red-brown pigment usually described. This 

 red pigment was formed in glycerol broth on the fourth day. 

 Acid and alkali seemed to suppress pigmentation, as did pure 

 oxygen. 



