139 



•JrO c. c. of the yellow acetone extract for some hours tobrisfht sunshine 

 on a tin roof, at 50° to 60° C, the fluid was reduced to 1 c. c, but 

 instead of being an intense yellow, as was expected, it became a very 

 pale yellow — i. e., there was less yellow in the 1 c. c. remaining than 

 in the same quantity of the original fluid. 



This color is not an oil, but seems to be intimately associated with 

 such a body. On evaporating a yellow acetone extract (organism 

 grown on sugar beet) to one-tenth or one-twentieth of its volume, the 

 perfectly clear fluid became whitish cloudy, like an emulsion, and on 

 examining it under the microscope it was seen to be composed of 

 innumerable round bodies having the optical and chemical properties 

 (osmic acid test) of oil globules. The yellow color was visible where 

 these globules were massed, and also in noncrystalline patches, but 

 separate oil globules did not appear to be yellow. 



On driving ofl' the remainder of the acetone with gentle heat, a 

 small amount of chrome yellow, oily looking and oily feeling fluid 

 remained in drops on the bottom of the white capsule. On adding 

 concentrated c. p. HgSO^ to these yellow wet-shining drops there was 

 an immediate decided blue-green reaction, which quickly changed to 

 brown and soon after to brown-purple. After one-half hour an oily 

 looking rim of brown-purple granules surrounded the drops of acid. 

 This purple color was also fugitive, fading to a dirty gray. The 

 acetone which was used changed to a clear brown on adding c. p. 

 HgSO^, but with no preliminary blue-green color. The yellow resi- 

 due which remained on evaporating the acetone extract from another 

 lot of cultures (organism grown on coconut) changed at once, on add- 

 ing concentrated c. p. HgSO^, into a green, which soon faded to purple. 

 On adding the acid directly to the bacterial slime dried on glass slides 

 it became orange-brown, then rusty-brown, and finall}^ rose-brown, 

 but no green or blue color appeared. 



The presence of highly organized nitrogenous bodies is not necessary 

 to the formation of this color. It is produced readily in Uschinsky's 

 solution, with starch substituted for glycerin, and on this medium the 

 yellow color is as pure and as bright as it is in the host plant or on 

 coconut, sugar beet, peptone agar, or sugar gelatin. 



These results lead me to think that this yellow color belongs to the 

 Lipochrome group of plant pigments. (See Zopf : Die Pilze, p. 144.) 



So far as I have tested it, the yellow pigment of Ps. campestrt's 

 l)ehaves in the same wa}^, i. e., it is soluble in glycerin, eXhyX alcohol, 

 methyl alcohol, acetone, ammonium carbonate in water, and glacial 

 acetic acid-, it is insoluble in sulphuric ether, chloroform, xylol, toluol, 

 or carbon bisulphide, but is bleached ))v these substances. As a rule, 

 the yellow color of /^v. hyacinthi is brighter than that of l^a. campestru 

 or P^. phaaeoii. 



