95 



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

 alike in color, but frequently the hyacinth germ was the Ijrighter 

 yellow. 



(2) The growth of Ps, ca7npestris, Ps. ^^^^^^seoli, and I^s. stewarti 

 was not retarded bN^ 9 per cent grape sugar. On the contrary, it 

 was stinuilated from the very start. At the end of the first 48 hours 

 on this agar Ps. cm/qjcstris showed about twice as much growth, 

 P^. phiiHwli ''more growth," and 7^6'. stewarti four times as much 

 growth as in the corresponding check tubes. On the seventh day Ps, 

 cuntpestris showed ten times as much growth as Ps. hyacinthl^ and 

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

 the sixteenth day). On this date Ps. 2)haseoli had made twice as much 

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

 On the same date Ps. stewarti had made at least five times as much 

 growth as in the check tube. 



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

 showed, on the third day, twice as nmch growth and Ps. lyhasecM 

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

 There was no retardation whatever. 



(3) Addition of 17 per cent grape sugar retarded the growth of 

 Ps. campestris and Ps. phaseoli (Ps. stewarti was not tried), but they 

 overcame the injurious influence sooner than Ps. hyacinthi. If the 

 volume of growth of Ps. hyacinthi on this agar on the sixth da}^ be 

 taken as 1, then that of Ps. camjMstris was 10 and that of Ps. p>haseoli 

 was 15 to 18. 



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

 growth of Ps. phaseoli and seriously retarded that of Ps. . camjjestris.^ 

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

 was overcome groAvth was greatly stinmlated. 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 b}' 6 to 8 mm. On the thirt3^-scventh 

 day growth liad doul>led, the streak now being 40 ])y 3 to 12 nmi. The 

 slime dissolved readily in water and consisted largely of chains 50 to 

 100 /^ long. In a repetition of this series of experiments, 23 per cent 

 grape sugar retarded Init did not prevent the growth of Ps. pliaseoli. 

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

 not appear until the fourth da}', and then only colony-wise. 



(5) On the 9 per cent (acid) fructose agar Ps. phaseoli refused to 

 grow. Ps. campestris obtained a precarious foothold, but grew only 

 a little. 



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

 growth of Ps. campestris or I^s. 2>haseoli^ at least, not to any notice- 



