95 



this agar in the presence of grape sugar or cane sngar. All were much 

 alike in color, l)ut frequently the hyacinth germ wa.s the brighter 

 yellow. 



(2) The growth of Ps, campestris, Ps. phaseoH, and Ps. steunrti 

 wa.s not retarded )>y 9 per cent grape sugar. On the contrary, it 

 was stinudated from the veiV start. At the end of the iirst 48 hours 

 on this agar P>i. cavipestris showed about twice as nmch growth, 

 Pa. phaHeoU "more growth," and /^v. xtewarti four times as nmch 

 growth as in the corresponding check tu])es. On the seventh da^^ Ps. 

 campestris showed ten times as much growth as J^x. /li/acint/ii, and 

 three times as nuu*h as in its own check tube (ten times as much on 

 the sixteenth day). On this date Ps. p/mseoli had made twice as much 

 growth as in the check tube (ten times as nmch on the sixteenth day). 

 On the same date Ps. steiiiarti had made at least live times as much 

 growth as in the check tube. 



In a second series of experiments with this agar Ps. campeatTis 

 showed, on the third day, twice as much growth and Ps. phaseoli 

 two and one-half times as much as there was in the check tubes. 

 There was no retardation whatever. 



(3) Addition of IT per cent grape sugar retarded the growth of 

 Ps. eamjjestris and Ps. phnseoli {Ps. stevMrtl was not tried), but they 

 overcame the injurious influence sooner than A-. hyacinthi. If the 

 volume of growth of Ps. kyacmthi on this agar on the sixth day be 

 taken as 1, then that of Ps. ccmipestris was 10 and that of Ps. ])haseoli 

 was 15 to 18. 



(4) Addition of 23 per cent grape sugar entirely prevented the 

 growth of Ps. phaseoli and seriousl}^ retarded that of Ps. eainpestris., 

 but did not prevent it. On the contrary, when the retarding influence 

 was overcome growth was greatly stimulated. On the seventh day 

 this growth was only about one-flfteenth as much as in the check tube, 

 or as on the 23 per cent cane-sugar agar. On the sixteenth day there 

 was a marked increase of growth, but there was not one one-hundredth 

 as nmch as in the corresponding tube of cane-sugar agar. On the 

 thirtieth day the streak was 23 by 6 to 8 ram. On the thirty-seventh 

 dav growth had doubled, the streak now being 40 bv 3 to 12 mm. The 

 slime dissolved I'eadily in water and consisted largely of chains 50 to 

 loo /Hong. In a repetitif)n of this series of experiments, 23 per cent 

 grape sugar retarded but did not prevent the growth of ]*s. phaseoli. 

 The surface was rubbed with loops from agar cultures, but growth did 

 not appear until the fourth day, and then only colony-wise. 



(5) On the 9 per cent (acid) fructose agai' I*x. pliaxeoll refus(>d to 

 grow. Ph. ca/rapestris obtained a precarious foothold, but grew oidy 

 a little. 



(iS) Addition of 17 or 23 per cent cane sugar did not retard the 

 growth of I*s. eawpestrix or ]*s. phaseoli^ at least, not to any notice- 



