31 



culture 8 days old, and in 28 hours, at 22° to 28°, when the inocula- 

 tion was made from an agar culture 13 daj's old. This orowth was 

 thin, distinctly yellow, smooth, wet-shining, translucent, homogeneous- 

 lookino-, and not scanty. There were no down-groAvths into the agar, 

 and the margins, while thin, were well defined, i. e., not nebulous. 

 Even on recent!}' slanted agar the organism showed little tendency to 

 spread widely. The streaks remained translucent for a long time, a 

 penhokler being easily visil)le through them after a month or more. 

 No crystals were formed and there Avas no ])rowning of the agar even 

 in old cultures. (An undescribed, white, endosporc-bearing Schizo- 

 mycete, isolated from rotting tomato fruits, lirowned this agar readil3\) 



After a month or two the streaks began to dry out, ])ut the surface 

 remained smooth, even in old cultures, and was homogeneous looking, 

 except that, after some weeks, colonies of the same species frequently 

 formed on the surface of the yellow slime. Tested on the seventeenth, 

 forty-seventh, and fifty-third days, with neutral litmus paper, the 

 slime was feebh^ to plainly alkaline. On the sixty-sixth day it was 

 stronglv alkaline. No acid reaction was ever observed. 



An extremely thin, whitish, chemical deposit appeared on the surface 

 of the agar beyond the streak, after a week or two, and slowly in- 

 creased, l)eing best developed on the lower part of the slant where the 

 growth was best. This film dissoh^ed in h) per cent acetic-acid water 

 in about one minute. 



On the fort3^-seventh day the slime consisted of short slender rods, 

 single or in pairs. Four rods joined end to end were rare, and chains 

 were A'er}' rare. After a long search oidy one chain was found (about 

 10 segments). In none oi these tubes did the growth increase much 

 after the second week, and it never became what might be called 

 copious. No reticulate or shagreen surface ever appeared in any of 

 these cultures. (See Sugar agars under Relative initrient value of 

 carbon compounds.) 



Streak cultures of T*s. eampesiris, Pi<. phaseoll., and occasionally of 

 Ps. stetvarti^ were made for comparison. The Ijehavior of these three 

 parasites on this agar was nmch the same as that of P.s. Ityacintlu. All 

 grew without retardation, and after a few days there was about the 

 same amount of smooth, translucent yellow slime. No crystals were 

 formed in the agar and no ])rown stain appeared, even in old cultures. 

 The whitish chemical film appeared around the streaks whichever 

 organism was used, and in some cases it was noted that it was best 

 developed in the lower part of the streak. In case of 7\-. camjyentris^ 

 this film was examined microscopicalh' and found to consist of very 

 minute granular bodies, which were readily soluble in 10 per cent 

 acetic-acid water, but did not show any decided crystalline structure 

 when examined with the polariscope. 



In one series of tubes, after five days on this medium, Pa. hyaclnthi^ 



