85 



(d) Coconut. — March 20, no growth, ^farch 21, extremely thin (barely visible) 

 buff-yellow growth over 3 sq. cm. Marcli 23, a thin, pale, buff-yellow growth now 

 covers a})out 5 sq. cm. INIarch 27, a rather scant buff-yellow growth over 8 sq. cm. 

 No retardation, 



B. a.nii/Iororus: 



(a) Agar. — ^Nlarch 20, no growth. March 21, a distinct growtli on the l<nver end 

 of the slant. INlarcli 23, the white growth slowly increases. 



This closes my studies of the aei'o])isin of 7 ^•. Injari nflil and related 

 species. All the various experiments lead to substantially the same 

 conclusions: (1) Px. hydcintJii and the other yellow species of Pseudo- 

 monas are more strictly aerobic than most species of bacteria; (2) while 

 somewhat variable among themselves none of these yellow-plant para- 

 sites will survive exclusion of oxygen for more than a very few weeks; 

 (3) nitrogen, hydrogen, and carbon dioxide seem to be onl}' negatively 

 harmful; (4) the organisms were more tolerant of these gases on some 

 mod ill than in others. They were especially susceptible in beef broth, 

 in peptone water, and on agar. 



RELATIVE NUTRIENT VALUE OF CARBON COMPOUNDS. 



BoriLLox AXD Peptone AYater with Various Sugars, etc 



The few results obtained ma}' be summed up as follows: 



(1) A feeble clouding was obtained with Ps. hyacinthi in a fluid con- 

 sisting of 1 part of strongh' alkaline beef broth (286b) in 500 parts of 

 distilled water. Ps. camjX-stris and Ps. 2^JiciseoH also clouded this Huid. 

 These cultures were made in clean tubes of resistant glass. 



(2) P^. JiyacintJrf grew readily in distilled water containing 1 to 2 

 per cent of AVitte's peptonum siccum, and the precipitate was yellow. 

 Growth in 1 per cent peptone water in the open end of fermentation 

 tubes, as we have already seen, was increased ])y the addition of 1 per 

 cent doses of grape sugar, fruit sugar, cane sugar, or dextrin, and 

 was not perceptibly increased by the addition of 1 per cent doses 

 of milk sugar, maltose, mamiitol. or glycerol. If under these condi- 

 tions any acid was formed fi'om any of these substances^ it was over- 

 looked or obscured by the alkali. 



(3) In distilled water (10 c. c. portions in tubes of resistant glass) 

 containing 4 per cent of Witte's peptomun siccum and 4 per cent of 

 dextrin there was little oi- no retardation of growth. On the twelfth 

 day the fluid was plainly alkaline to litnms. On the twenty-ninth 

 day there was an abundant yellow rim and a very copious dull-yellow 

 precipitate (♦> nun. dee})). The cloudy fluid was plainly and rather 

 strongly alkaline. On this date there was several times as nmch pre- 

 cipitate^ as in the corre>])ondi.ig tubes of 7^'. camjx'stris and Ps.j)/H(Scoli. 

 On the fortieth dav the fluid was strongly alkaline. It was still cloudy 

 with rolling clouds on shaking, and there was no brown stain in it. 

 On the sixty-fifth day the fluid was moderately alkaline. No ciystals 



