89 



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

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

 principal difference l>eing the tendency to longer chains or filaments. 



Second series. 



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

 moistest. Inoculations from a slant-agar culture of Ps. hyadnthi 13 days old. All 

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



Third day. 



(1) Check.— 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 {1 gram of Schrring'n 'Jiabetine). — No growth, although inoculated 

 just as copiously. 



(3) Grape sugar [1 gram of MercF x c p. a)ihf/drous).—A ieehXe 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) Crra;je A-Np-t/r.— 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 paper. 



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) Fruit sugar. — No growtli. Fragments of the moist agar pressed on neutral 

 litmus paper redden it. 



(3) GrajK 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 V)rown stain in the agar. 



Fifty-third day. 



(1) Check. — Slime feebly alkaline. 



(2) Fruit sugar.— 1^0 growth. Failure to grow was attributed to the' restraining 

 influence of lactic acid juit into this sugar by the manufacturers to improve its 

 keeping iiualities. 



(3) (Iraj)i' sugar. — Streak somewhat wrinklc<l and on the margins slightly areolate. 

 Slime now distinctly acid to lunifral litmus paper, no trace of any alkaline reaction. 

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

 neutral or oidy very feebly aciil. On boiling this watei- a little acid is given off in 

 the first vapors (CCy), but less than from a corresponding culture of Ps. canipestris. 

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

 litmus ])aper, indicating the i)reseiu'e of a small anioiuit of some non-volatile acid. 

 Cultures of Ps. camjjcslris behaved in the same way. 



