60 



Result. — Two of these groups of tubes failed to catch and were 

 reinoculated later so that the first group will ]>e considered b}^ itself. 



(1) These 2 tubes were inoculated in the same wa}^ from a fluid 

 culture 32 da3^s old. During the first 18 days there was no trace of 

 color or sign of growth in the check tube. On the twent}^ -seventh 

 daj^ there was a slight growth with feeble yellowing of the surface, but 

 careful scrutiny was necessary to detect it. On the thirty-fifth day a 

 slight increase of growth was noted. The starch had not dried out 

 much and the whole of it was still bluish white, indicating that there 

 had been no considerable diastasic action. The streak was very thin, 

 ver}^ pale yellow, did not hide the substratum, and had no well-defined 

 margins. On the sixty-second day there was decidedly more growth, 

 the whole surface being covered with a thin, distinctly yellow, smooth, 

 homogeneous, wet-shining layer. The body of the starch still pre- 

 served its bluish white luster and retained its water well. The amount 

 of growth in this tube after 62 da^^s was not greater than that present 

 in the other tube at the end of 5 days. In the tube which received 

 the diastase there was, on the fifth day, a distinct but not very copious 

 growth, covering about two-thirds of the slant surface. On the 

 twelfth da}" there was an abundant bright yellow growth covering the 

 whole surface and affording a striking contrast to the check tube. 

 This contrast continued for some time, the difi'erence in the 2 tubes 

 on the fourteenth da}^ being shown in figs. 15 and 16 of the plate 

 accompanying bulletin 26 of this Division. The color was approxi- 

 mately Ridgwa3^'s canary yellow (VI-12). On the twenty-seventh da}" 

 the slime was still bright yellow, and the amount of growth was esti- 

 mated at 200 times that in the check tube. On the thirty-ninth day 

 there was still no brown stain. 



(2) After 8 days the other 1 tubes were reinoculated copious!}' over 

 the whole surface with yellow slime taken from the culture just 

 described. They were under the same conditions as to light and tem- 

 perature, the greatest difi:'erence between these and the preceding- 

 being the enormous number of germs used in making the inoculation. 



Result. — The 2 check tubes behaved alike. On the fourth day there 

 was a trace of yellow growth at the bottom of the slant, but it was 

 feeble, and was visible on not more than one-fiftieth of the Avhole sur- 

 face. At this time the tubes which received the diastase showed an 

 abundant bright yellow growth over the whole surface, a growth several 

 hundred times as abundant as that in the check tubes. On the sixteenth 

 day, in the check tubes, there was only a feeble growth of 9 or 10 square 

 millimeters. This growth was bright yellow, but it was not one one- 

 hundredth as nmch as in the tubes which received the diastase. On the 

 twenty-seventh day, in the check tubes, the growth had dou])led, but 

 the substratum was hidden only over a few square millimeters, and the 



