89 



the chains, but not all, the individual elements are visible. No spores. The micro- 

 scopic appearance closely resembles that of the slime from the grape-sugar agar, the 

 principal difference being the tendency to longer chains or filaments. 



Second series. 



The check tube had the driest surface; the surface of the fruit-sugar agar was the 

 nioistest. Inoculations from a slant-agar culture of Ps. hyar'nitJii 18 days old. All 

 made in tlu; same way and with approximately the same amount of material. 



Third day. 



(1) CJirH-. — Streak 78 by 5 to 12 mm., pale yellow, translucent, smooth, wet- 

 shining, homogeneous looking, and not scanty, i.e., a good growth over the whole 

 length of the slant. 



(2) Fruit sugar {l gravi of ScJiering's diahetine) . — No growth, althougli ino(;ulated 

 just as coj)iously. 



(3) Grape sugar {1 gram, of MercFs c. p. anhydrous). — A feeble growth consisting 

 of scattered colonies which, in some places, have fused into a very thin layer. Not 

 one-twenty-fifth as much growth as in the check tube. Grape sugar in 9 per cent 

 doses distinctly retards growth. (This growth doubled during the next 24 hours.) 



Fifth day. 



(1) Check. — Much as before. 



(2) Fruit sugar. — No growth. 



(3) Grape sugar. — There is now nearly as much growth as in the check tube. The 

 lower one-half of the slant is covered, and the upper one-half bears scattering yellow 

 colonies. The surface is not smooth, as in the check tube, but is distinctly shagreened 

 to the naked eye. The yellow slime is very feebly alkaline, inducing only the barest 

 trace of blue on wet or dry neutral litmus jmper. 



Eighteenth day. 



(1) Check. — A thin, smooth, moist, pale-yellow slime covers nearly the entire 

 slant. There is no brown stain in the agar. 



(2) FHiit sugar. — No growth. Fragments of the moist agar pressed on neutral 

 litmus paper redden it. 



(3) Grape sugar. — A copious, pale-yellow, coarsely wrinkled growth now covers 

 the whole slant. This layer scrapes off easily, and is very feebly alkaline to neutral 

 litmus paper. There is no brown stain in the agar. 



Fifty-third day. 



(1) Check.— ^Vime feebly alkaline. 



(2) Fruit sugar. — No growtli. Failure to grow was attributed to the restraining 

 influence of lactic a(Md put into tliis sugar by the mamifacturers to improve its 

 keei)ijig qualities. 



(3) Grape sugar. — vStreak somewhat \vrinklc<l and on the margins shghtly areolate. 

 Slime now distinctly acid to neutral litnuis paper, no trace of any alkaline reaction. 

 Culture diluted (shaken) with 40 c. c. of distilled water and retested. It is now 

 neutral or only very feebly acid. On boiling this water a little acid is given off in 

 the first vapors (CO.^?), but less than from a corresponding culture of Ps. campestris. 

 On concentrating this fluid by continued boiling it became plainly more acid to 

 litnms paper, indicating the presence of a small amount of some ncm-volat-ile acid. 

 Cultures of Ps. catujicstrls behaved in the same way. 



