STEWART'S DISEASE OF SWEET-CORN (MAIZE). 1 39 



(i) In the first experiment there was no growth on potato and a decided retardation after breaking the seal; in 

 beef-broth there was either no growth, or only a trace of growth, but no retardation on exposure to the air; on slant agar 

 there was a distinct, very feeble growth, consisting of several hundred tiny whitish colonies, best seen under the hand- 

 lens. On exposure to the air these colonies enlarged and became burl-yellow. 



(2) In the second experiment, which also lasted 16 days, there was no growth in +15 beef-broth, and no retarda- 

 tion of growth on subsequent exposure to the air. In peptone-water with grape-sugar and methylene blue there was a 

 trace of growth, and no marked retardation on exposure to the air. In salted peptone-water (Dunham's solution) with 

 rosolic acid there was no growth, and not much afterward. In Uschinsky's solution there was no growth and none 

 afterward in the air. 



Each of these tubes received a 2-mm. loop from a cloudy culture 5 days old in peptonized beef-bouillon neutral to 

 phenolphthalein, and it was known by previous tests that the organism grew well in these media. 



During 10 days' exposure to an atmosphere of carbon dioxide there was no growth. On subse- 

 quent exposure to the air there was no retardation of growth on the coconut, some retardation on 

 potato, and no growth in beef-broth. 



In a second test in carbon dioxide (14 days) there was no growth whatever on potato or in 

 bouillon. The checks grew. I find no record of the subsequent behavior of the exposed tubes. 



Growth in vacuo depends entirely on the degree of exhaustion. 



In a vacuum with the mercury at 2.25 inches, the remnant of the oxygen having been absorbed 

 by pyrogallol in caustic-potash water, there was no growth during the 9 days' exposure, and a distinct 

 retardation of growth after removal to the air. The four corresponding check-tubes (2 coconut, 2 

 potato) showed a distinct buff -yellow growth in 48 hours. 



In a second test on coconut, potato and carrot, and in alkaline beef-bouillon, the jar being sealed 

 with the mercury at 3 inches and the remnant of the oxygen not removed, there was a slight, retarded 

 growth, paler than on the checks and less in amount. The check-tubes showed a good growth at 

 the end of the third day, and a plainly visible one in 48 hours. On the twelfth day, when the seal was 

 broken, conditions were as follows: 



Carrot. Merest trace of growth. 



Potato. About 0.33 to 0.50 as much growth as on check; potato not grayed. 



Coconut. Thin cream-colored growth. The check is buff-yellow and contains several times 

 as much growth. 



Beef -broth. Very feebly clouded. The check is twice as cloudy and contains twice as much 

 bacterial precipitate and this is yellower. 



All of these cultures made additional growth on exposure to the air. 



No acid reaction was obtained when Bad. stewarti was grown in bouillon containing glycerin or 

 ethyl alcohol. 



In culture-media in the presence of air, this organism breaks up the following substances with- 

 out gas, but with the formation of a small quantity of non-volatile acid : grape-sugar, cane-sugar, 

 galactose, mannit. 



In a repetition of these tests in 1908, using Bad. stewarti from three sources and streaking on 

 litmus agars containing only agar, water, Witte's peptone, and the specified sugar or alcohol, and 

 inoculating copiously (two 3 mm. loops) from bouillon cultures 3 days old, the following results 

 were obtained: End of 48 hours distinct growth, but no reddening either with plain agar or that 

 containing dextrose, lactose, galactose, maltose, mannit, or glycerine. Most growth on that con- 

 taining the cane-sugar, and on this a trace of red at the extreme top of the slant. On the eleventh 

 day the conditions were as follows : 



(1) Plain agar. Bluer than checks. Rather feeble growth. 



(2) Dextrose agar. Two strains bluer than checks, except for dab of red in one at extreme top. Third (a weaker 



strain in other media) dull red throughout. 



(3) Lactose agar. Two are bluer than checks, except dabs of red at extreme top of slant. Third (weaker strain) purple- 



red in upper two-thirds (in upper one-third 4 days earlier). 



(4) Galactose agar. Each dull purple-red. Redder than checks but not bright red. The checks were a blue purple. 



(5) Maltose agar. Each tube is bluer than the checks. This was also true 4 days earlier. 



(6) Mannit agar. Distinctly bluer than the checks, but a dab of red at extreme top of one tube (not the weaker). This 



was not present 4 days earlier. 



(7) Glycerin agar. -The litmus is now a dull purple-red. It was neutral 4 days earlier. Slight acid formation, per- 



haps C0 2 . 



(8 ) Sacchirose agar. -Each uniform in color and bluer than the checks, except for a dab of red at the extreme top of each 



slant where the agar is drying out. Here would seem to be an acid masked by an alkali. 



In salted peptone-water (Dunham's solution) containing rosolic acid and a slight amount of 

 hydrochloric acid (color of fluid a pale orange-yellow) there was no decided change during the first 

 two weeks, but on the twenty-eighth day the fluid was pale red, and subsequently geranium red. 

 This medium would serve to differentiate Bad. stewarti from Bad. hyacinthi and Bad. campestre, 

 cultures of the former being colorless and cultures of the latter geranium red at the end of the second 

 week. 



