92 



two places, aggregating 2 square cm. "Where the organism has secured a foothold the 

 slime is distinctly pale yellow, but much of the part which was streaked hears no 

 growth whatever, and altogether there is not one-tenth as much growth as in the check 

 tube. The surface of this slime is not smooth, as in the check tube, but is mmutely 

 fissured and roughened all over. 



(3) Cane augar. — As much growth as in the check tube, but paler yellow. Thus 

 far the sugar has not stimulated growth. The streak is now 5 to 9 mm. wide. It 

 has thickened some since the last record, but has not widened much. 



Thirteenth, day. 



(1) ('heel:. — Streak well developed, smooth, wet-shining, and distinctly yellow. 

 The margins are well defined, and the body of the streak is not opaque, i. e. , the pen- 

 holder can still be seen through it. It shows very little tendency to spread, i. e., it 

 is still only 5 to 7 mm. wide. There are no projections from the under side of the 

 streak into the agar (such growths appeared in case of an undescriVjed, white, spore- 

 bearing organism, derived from rotting tomato fruits, and grown on this .same agar). 

 There is now a slight but distinct bloom (chemical whitening) on the surface of the 

 agar beyond the streak. 



(2) Grape augar. — About one-tliird, or i)Ossil)ly one-half as much growth as in the 

 check tube. The color is the same, but the surface appearance is very different. 

 The wet surface is not smooth, but is roughened, or areolated, as if made up of fused 

 zooghe.'e with grooves between them. There is no chemical whitening of the sur- 

 face of the agar beyond the streak. 



(3) Cane sugar. — Streak mostly 6 to 10 mm. wide. Surface drier and paler yellow 

 than in the preceding or in the clieck tube. No growths into the agar from the 

 under surface of tlie streak. Seventeen per cent cane-sugar agar is not nearly so 

 favoraljleto the growth of this organism as 9 per cent. There is now but little more 

 growth than in the check tube, whereas on the 9 per cent cane-sugar agar there was 6 

 times as much growth in one-half this time, the temperature in both cases being 

 approximately the same, i. e., near the optimum. 



Seventeenth day. 



(1) Check. — The yellow slime is jilainly alkaline to good neutral litmus paper, much 

 more so than that on the grape-sugar or cane-sugar agar. 



(2) Grape sugar. — Slime neutral or very slighth' alkaline. 



(3) Cane sugar. — Slime neutral or only very slightly alkaline. 



Thirtieth day. 



(1) CIterk. — The streak begins to dry out. Its surface is smooth. There has been 

 no widening. Beyond the streak the whitish chemical film remains, but is not very 

 pronounced. No brown stain. No crystals. 



(2) Grape .'ill gar. — A pale yellow well-developed .<treak (50 by 5 to 9 mm.). It has 

 not spread widely, and is still translucent. The surface is rather coarsely roughened 

 and looks as if many large zooglcese had fused, leaving grooves between each one. 

 The surface of the individual hummocks is smooth, wet-shining, firm, elastic, and 

 scrapes off only after the use of considerable force. Examineil under the micro- 

 scope, this growth consists of slender rods mixed in with some chains. The rods are 

 single, in pairs, and in fours joined end to end. There is no brown stain. 



(3) Cane sugar. — The growth is now two or three times as abundant as in the check 

 tube. It is very dense, especially on the lower part of the slant, where it is crowded 

 up into high folds. The upper part shows lesser wrinkles. No brown stain and no 

 chemical film on the clear agar to either side of the streak. The slime is pale yellow 



I 



