BACTERIA OF PLANT DISEASES. 573 



jecting part of the cylinder was covered with a copious, wet-shining growth. 

 At first this growth was white or dirty white, but after some days (three to 

 ten) it became brown, and finally, in places, nearly or quite black (smoke 

 brown is perhaps the proper term). The growth on potato was not wrinkled. 

 The substratum and the fluid in the bottom of the tube also became brown. 

 The rapidity and the degree of pigmentation seem to depend on the slightly 

 varying composition of the potato, apparently on the amount of glucose 

 present. No gas was formed in any of the many potato cultures. No acid 

 was detected in any stage of the growth of the cultures, not even when tested 

 at the end of the first twenty-four hours. The potato cultures, which were 

 slightly acid on the start (normal acidity of the tuber), soon became strongly 

 alkaline to litmus paper. With Nessler's solution the alkaline potato cultures 

 gave an immediate,* copious, orange-yellow reaction, indicating ammonia. 

 These cultures developed a peculiar odor, often noticed in rotting potatoes, 

 but not specially disagreeable. This odor was likened by one person to the 

 smell of sour bran. Its chemical nature has not been determined. The 

 cylinders did not fall into pieces, but retained their shape for several 

 weeks. 



44 Gas Production. No gas appeared in any of the many cultures. The 

 organism is not a gas producer. 



"Relation to Oxygen. This bacillus appears to be strictly aerobic. If 

 ever facultative anaerobic, it is not so with any of the carbohydrates yet 

 tested. 



"Acids No acid reaction could be detected in any stage of any of the 

 cultures. Potato cultures only twenty-four hours old and which were acid 

 on the start (normal acidity of the tuber) gave a decided alkaline reaction to 

 litmus paper. If any acid whatever is formed it is masked by the presence 

 of alkali and is not butyric acid. 



"Alkalies. This organism is a very vigorous alkali producer. On 

 warming the cultures over a gas flame or on placing the blued strips of 

 litmus paper 011 a warm glass plate the alkaline reaction quickly disappears. 

 On adding a few drops of Nessler's reagent, as already stated, a copious 

 orange-yellow precipitate is at once developed. This would indicate that at 

 least a part of the alkali is clue to ammonia. Probably amiiie bases are also 

 present. 



kk The bacillus grows well in the thermostat at 37 C. possibly a trifle 

 better than outside at summer temperatures ranging from 25 to 32 C. 

 Under either condition it grows rapidly. It still grew readily from bouillon 

 cultures after several weeks' exposure to 37 D C. (three weeks' exposure in 

 one case, seven weeks' exposure in another). 



"Pigments. A brown pigment is formed in course of a few days in the 

 host plants (potato, tomato, etc.), and in culture media containing grape, 

 fruit, or cane sugar (nutrient agar, steamed potato, fermentation tubes). 

 This pigment is soluble in water and glycerin. It is insoluble in ethyl alco- 

 hol, ether, chloroform, xylol, and carbon bisulphide." 



"BACILLUS HYACINTHI (Wakker). 



" Pseudomonas hyacinth! (Wakker). A yellow, rod-shaped organism, 

 multiplying by fission ; ends rounded ; single, in pairs, or fours, more rarely 

 in the form of chains or filaments ; motile by means of one polar flagellum. 

 In the host plant, when the bundles are crowded full of the yellow slime and 

 broken down, it is generally 0.8 to 1.2 by 0.4 to 0.6 /<. In alkaline beef 

 broth or on agar it usually "measures 1 to 2 by 0.4 to 0.6 /^. In old cultures 

 rich in sugar it often grows out into long, slender chains, or into filaments 

 (50 to 100 p long) in which there are no distinct septa. Non-sporiferous. Color 

 distinctly yellow, but somewhat variable. Chrome yellow to pale cadmium 

 in the host plant, i.e., bright yellow (Ridgway's nomenclature of colors). 

 On culture media, when not interfered with by the brown pigment, generally 



