31 



culture 8 day.s old, and in 2S hours, at 22° to 28°, wlicn the inocula- 

 tion was made from an agar culture 13 daj^s old. This growth was 

 thin, distinctl}^ yellow, smooth, wet-shining, translucent, homogeneous- 

 looking, and not scanty. There were no down-growths into the agar, 

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

 Even on recently' slanted agar the organism showed little tendency to 

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

 penholder being easily visible through them after a month or more. 

 No cr3'stals were formed and there was no browning of the agar even 

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

 mycete, isolated from rotting tomato fruits, browned this agar readily.) 



After a month or two the streaks began to dry out, but 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 daj^s, with neutral litmus paper, the 

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

 strongh' 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, being best developed on the lower part of the slant where the 

 growth Avas best. This film dissolved in 10 per cent acetic-acid water 

 in about one minute. 



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

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

 were A'ery rare. After a long search only one chain was found (about 

 10 segments). In none or 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 nutrient value of 

 carbon compounds.) 



Streak cultures of Ps. campestris, Ps. pliaseoli^ and occasionally of 

 Ps. steficarti^ were made for comparison. The l)ehavior of these three 

 parasites on this agar was nmch the same as that of Pa. liyacintld. All 

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

 same amount of siuooth, translucent yellow slime. No crystals Avere 

 formed in the agar and no In'OAvn stain appeared, CA'en in old cultures. 

 The Avhitish chemical film appeared around the streaks whichever 

 organism Avas used, and in some cases it AA^as noted that it Avas best 

 developed in the loAver part of the streak. In case of 7^s'. canijjestrls^ 

 this film Avas examined microscopically and found to consist of very 

 minute granular bodies, Avhich Avere readily soluble in 10 per cent 

 acetic-acid Avater, but did not shoAV anv decided crystalline structure 

 Avhen examined with the polariscope. 



In one series of tubes, after five day.s on this medium, Ps. hyaclnthi^ 



