THE NITRIFYING PROCESS AND ITS SPECIFIC FERMENT. 
115 
These bottles were kept in the dark at the ordinary temperature of the laboratory, 
and when examined on April 5, 1888, they were all found to give strong reactions 
both with diphenylamine and sulphanilic acid. 
In this series the dilution employed had, therefore, been insufficient, but No. 5 
bottle, which had received only one drop, would obviously be likely to be the purest 
of the series. 
Plates were poured from this No. 5 bottle as the purest, and from the resulting 
colonies obtained a number of bottles containing sterile ammoniacal solution were 
inoculated, but in no case was nitrification induced. 
Dilution Experiments, Series III., commenced April 7, 1888. 
No. 5 bottle, as the purest of the last series of experiments, was taken as the 
starting-point for this series. 1 drop from this bottle was diluted with 50 c.c. of 
sterilised distilled water, and from thisyr»’^ dilution 3 bottles (Nos. 1, 2, and 3), con¬ 
taining sterile ammoniacal solution, were inoculated with 1 drop each. Each of these 
bottles thus received about xoVo drop of the original solution (bottle No. 5 above).* 
Further 5 c.c. of the above “first dilution” were diluted to 50 c.c. with sterile 
distilled water, and from this second dilution a bottle No. 4 was inoculated with '5 c.c. 
(or T^o drop of original solution), a bottle No. 5 with 1 c.c. (or drop of original 
solution), a bottle No. 6 with 2 c.c. (or xxo drop of original solution), and a bottle 
No. 7 with 3 c.c. (or drop of original solution). 
The whole series thus consisted of— 
No. 1 bottle containing about drop of nitrifying solution. 
„ 2 
55 3 
55 4 
55 5 
55 6 
„ 7 
5? 
1? 
?? 
)1 M 55 55 
55 5 1 
55 5 0 0 
55 2 5 0 
_ 1 _ 
55 16 7 
55 
55 
55 
55 
55 
55 
55 
55 
All these bottles were kept at 15-20° C. and were found to have nitrified when 
examined on May 10, 1888. 
Thus, again, the dilution had been inadequate for assured isolation, but bottles 
Nos. 1-4 would obviously be likely to contain the nitrifying organism in a greater 
state of purity than the remainder Nos. 5-7. One of these purest bottles was, 
therefore, made the starting-point for the next series of experiments. 
Ddution Experiments, Series IV., commenced May 12, 1888. 
One of the presumably purest bottles of the previous series was made the point of 
departure for the renewed attempt at isolation. 
* In this and subsequent calculations it is assumed that I c.c. consists of about 20 drops. 
Q 2 
