41 



thick slime was acid to litmus, especially when diluted with distilled 

 water. The tissues were softened and there was a peculiar smell, which 

 was not rank or strong. 



The behavior of Ps. steivarti on this substratum differed from that 

 of Ps. Jtyacintld and Ps. campestHs in the same way as on the yellow 

 globe turnip and was even more pronounced, so that it might be used 

 as a means of distinguishing these organisms. The growth on the 

 seventh day was about one-tenth as much as Pi<i. hyacintJil and one- 

 twentieth or one-thirtieth as much as Ps. carajpestms. 



On the eighteenth day the differences were as follows: 



7^-. .steicartt: Growth. Iniff yellow, thin, covering the whole of the 

 air-exposed surface, but not dense enough to hide the slight irregu- 

 lariries of the substratum (not smooth). Surface slightly iridescent 

 and with tine stride (Zeiss X C aplanat). precipitate buff' yellow and 

 moderate in amount, water not grown full of the solid yellow slime, 

 substratum not l)rowned. 



J\. hyarintJif and Ps. cainjK.strls: Slime in the air copious, smooth, 

 very wet-shining, pale yellow, surface not iridescent. Fluid grown 

 full of the yellow slime (solidified). Su1)stratum browned or ready to 

 brown. 



In old cultures of Ps. steirarti there was no increased growth, no 

 brown stain, and no softening of the tissues. On the thirty-fourth 

 day the thick slime would not wet litnuis paper until water was added, 

 when it gave an alkaline reaction. On the sixty-fourth da}^ there was 

 ''a peculiar smell*' and a feebly alkaline reaction. The iridescence 

 persisted. 



Carrot. 



C^dinders of carrot were prepared in the same way as the potato 

 cylinders. 



l*s. liyaelntJt) grew well on this medium at 20^ to 23^ C. and gen- 

 erally without any distinct retardation. Usually growth was visible 

 on the third day. and continued for several weeks, covering the aerial 

 part of the cylinder with a bacterial layer a millimeter thick. The 

 fluid in the bottom of the tube (1 to 2 c. c.) was also tilled with a thick 

 3'elloM- slime, so that after 3 weeks it could usually be turned bot- 

 tom up without flowing. Generally, though not alwa3's, growth was 

 copious enough by the end of the tirst week to obscure the orange red 

 of the substratum, which was not the case with Ps. camjyestris. 



The surface was always wet-shining, even in very old cultures. In 

 some it was smooth and homogeneous-looking from the start, and 

 remained so. In others the surface was shagreened at flrst, ))ut after 

 eight days Vjecame smooth and homogeneous-looking. The bacterial 

 slime was not sticky on the eighth day, in which particular it is very 

 unlike Bacillus irachtipJrllus. Subsequently (thirty-flrst and sixty- 

 seventh days) it became slightly .sticky. 



