140 



The Bkown Pigment. 



Under certain circumstances, not clearly understood, a pale brown 

 pigment, soluble in water, is also produced b}^ Pa. hyacinthi. 



This feeble brown stain occurs in the host plant; in hyacinth broth; 

 in alkaline peptonized beef broth (after 5 or 6 weeks); in one-half 

 strength potato broth with 1 per cent Witte's peptonum siccum (not 

 when the peptone is omitted); in the same peptone potato broth with 

 addition of malic acid; on radishes (49 da3^s, not in 25 days), white 

 turnips, and yellow turnips; on banana pulp and banana rinds; and in 

 water surrounding potato cylinders, the potato itself being grayed. 



This pigment did not appear in any of the following media, not 

 even in yqvj old cultures: Acid beef broths (55, 59, 75, 80 days); alka- 

 line beef broths free from peptone (33, 67, 71, 97, 100, 119 days); alka- 

 line beef broth w4th cane sugar (26, 39, 67, 82, 98 days); distilled 

 water with 1 per cent maltose, 1 per cent dextrine, and 1 per cent 

 Witte's peptone (29, 40 days. Doubtful at the end of 70 days — no 

 brown stain in one tube and a slight (?) browning in the other); 4 per 

 cent peptone water (15 days); one-half strength potato broth (73 days); 

 the same with small amounts of caustic soda (59,73 days); Uschinsky's 

 solution (83 days); standard agar containing some muscle sugar, acid- 

 it}^ +22 of Fuller's scale (22 daj^s); standard agar containing no 

 muscle sugar, acidit}^ +15.5 (13, 18, 47 da^^s); the preceding agar with 

 grape sugar (18, 29, 47 da^^s); the same with cane sugar (29. 47 da^^s); 

 the same with fructose (31 days); litmus alkaline gelatin (39 days); 

 malic acid gelatin (34 da3"s}; malic acid gelatin wdth cane sugar (174 

 days); gelatin neutral to phenolphthalein with soda (87 days); the same 

 with cane sugar (61 days); sugar beet (55, 60, 67, 70 days); coconut (49 

 da^'S, 95 days); potato with cane sugar (2 tubes, 67 da3's — a third tulie 

 showed slight browning on sixty-seventh day, but less than tubes 

 without the sugar); nutrient starch jelly made from Uschinsky's solu- 

 tion b}^ substituting washed potato starch for the glycerol (35, 62 

 days); the same with Taka diastase (39, Q^ days); the same with malt- 

 ose (30 days); the same with dextrine (30 days). 



In the inoculated hj^acinth plants the brown stain was not very 

 noticeable, being confined, so far as observed, to the vascular bundles 

 of the diseased leaves, and easilv overlooked. In nutrient media the 

 pigment does not appear immediately and is best observed in old cul- 

 tures (1 to 3 months). It is never as pronounced, either in the host 

 plant or on culture media, as the similar pigment formed by Ps. cam- 

 joestris. The most decided browning Avas in old cultures on crucifer- 

 ous substrata and on banana skins. My failure to obtain any brown- 

 ing in gelatin cultures contradicts Dr. Wakkers statements, but this 

 contradiction maybe apparent rather than real — i. e., dependent, pos- 

 sibly, on differences in the chemical composition of the nutrient gela- 



