Mayi3, i9i8 Some Bacterial Diseases of Lettuce 375 



Pseudozoogloeae occur and are composed of masses of short and long 

 chains hanging together by a network of gelatinous threads. No long 

 filaments or queer-shaped cells were noted. Swollen cells and others 

 much reduced in size were noted in old cultures grown under low-tem- 

 perature and high-temperature conditions, acid-media cultures, and 

 cultures with sodium chlorid. 



BEHAVIOR TOWARD STAINS 



The organism stains readily and uniformly in the common anilin stains, 

 such as gentian violet, methyl violet, dahlia, and carbol fuchsin. It is 

 Gram-negative, and is not acid-fast. 



CULTURAL CHARACTERS 



Sterile potato cylinders proved to be a veiy- good medium for this organism, the color 

 of the bacterial slime being a bright yellow. Beef bouillon and litmus milk were 

 favorable media for prolonged grov/th. 



Beef-agar PLATES. — The colonies on peptonized beef-agar plates (4-15 Fuller's 

 scale) are visible in 24 to 48 hours, room temperature 20° to 25° C, when poured from 

 a young bouillon culture. They are at first a light-cream color, smooth, thin, round, 

 edge entire with light and dark areas in a sort of hourglass arrangement. These areas 

 disappear when colonies are 2 to 3 days old. Most of the colonies are cream color ^ 

 throughout; some have blue areas or a ring of blue color with a cream center when 

 viewed in transmitted light. When they are 4 to 5 days old, they are all a deep 

 cream-yellow color, and from 3 to 6 mm. in diameter. Buried colonies are round 

 or elliptical (PI. 35, C). 



Ag.\r stroke. — In two days at 25° to 28° C. there is a moderate, cream-yellow 

 growth, thin, flat, spreading, opaque, smooth, entire margin, viscid, yellowish in 

 condensation water. Crystals abundant in three days. GrowiJi remains moderate. 

 Agar does not change color. 



Agar stab. — There is very little growth in tv/o days; in three days a fair amount 

 of surface growth, faint filiform growth along line of puncture. Q)lor of growth, 

 honey-yellow. Crystals occur in agar just below the surface. In 14 days the color 

 of the growth is old gold, and the crystals extend down into the agar near the puncture. 

 In 30 days the growth is mustard color, and prismatic crystalsoccur throughout the agar. 



Beef bouillon. — Peptonized -1- 15 beef bouillon is clouded faintly in 2 days at 

 room temperature (25° to 28° C). At 3 days most of the growth is at the surface 

 until tube is agitated, and then the growth falls in tiny filmy flakes. No color change. 

 In 8 to 10 days there is an interrupted pellicle, and the bouillon is yellowish, with a 

 viscid sediment. In 41 days the pellicle is still incomplete, with long filaments 

 hanging down in the medium. There is usually a yellow rim and a heavy viscid 

 sediment in the bottom ; the rest of the culture is usually clear and in color is old gold. 



Neutral beef bouillon. — In 3 days there is a faint growth at a temperature of 22° 

 to 26° C, in 5 days a fair growth, and at 10 days a pellicle which sinks in long strands 

 on handling the tube. 



Bouillon containing sodium chloric. — In 4 days there is slight growth in 

 neutral beef bouillon containing 3 per cent of sodium chlorid. In 7 days there is a 

 good growth. No growth occurs in the bouillon to which 4 per cent of sodium chlorid 

 has been added. 



1 The colors mentioned in this paper are given according to Ridgway (Ridgway, Robert. C01.OR 

 Standards and Cou>r Nomenci.aturB. 43 P-. col- Pl- Washington, D. C, 1912). 



