| Tue NatTuRE AND REACTION OF WATER FROM HyDATHODES . 9 
until it was about the same as that of the expressed sap of much older 
plants as determined by Haas. The reaction of the water from maize, 
timothy, and oats grown on a similar medium was not the same; the water 
from maize became considerably more acid than that from timothy or 
oats. 
The hydrogen ion concentration of exuded water from timothy plants 
grown on a number of substrata suggests that with young plants the 
substratum makes very little if any difference in the hydrogen ion con- 
centration. Probably the temperature and light conditions also are factors 
which operate to change the hydrogen ion concentration. 
WATER FROM HYDATHODES AS A MEDIUM FOR BACTERIAL GROWTH 
In a test to determine the extent of bacterial growth on water from hyda- 
thodes, 0.002 cubic centimeter of the exudate water from non-sterile maize 
was spread over 1 square centimeter -of surface on a microscopic slide. 
After the water had spontaneously evaporated, the slide was passed 
through a flame and the residue was stained with Ziehl-Nielson carbol- 
fuchsin. On examining this under the microscope it was observed that 
the natural contamination of the material as collected was less than 
500. bacteria per cubic centimeter. Some of this exudate water was 
incubated for forty hours at room temperature, and the organisms then 
present were again determined. By that time such a heavy growth of 
bacteria had developed that the solution was very cloudy and an examina- 
tion similar to the preceding showed more than 100,000,000: bacteria per 
cubic centimeter. A series of plates were made in order to determine 
the number present by this method. The plate counts showed more 
than 90,000,000 bacteria per cubic centimeter. A part of one colony was 
transferred to a slope and used subsequently in determining the growth 
of the organism in sterilized exudate water from lawn grass (table 3, H). 
Water was collected from grass growing around the buildings on the 
campus. This was filtered through paper after the paper and the funnel 
had been thoroughly washed with distilled water and drained free of 
excess water. It was then distributed into carefully cleaned test tubes. 
sterilized, and inoculated with certain bacteria, the growth of which 
was determined. ‘The result is given in table 3: 
TABLE 3. Growrs or Bacterta IN HypATHODE WATER FROM GRASS ON Campus LAWN 
(Incubated at 25° C.) 
Number | Bacteria | Bacteria 
O i of bacteria joe Ges. per cc. 
eae introduced 24 hours | 48 hours 
per ce. later | later 
INITRETEE HHS) TRe10 NO UGSe ore ee ee eI oo Ee 19,500 | 44,500,000 | 103,000,000 
BESOIN TUSE CER CUS Peres rs 4 cistione 5 asf acl clone « 65 1,750,000 900 , 000 
3, UMGICSETIS ~ 5. BREE EE Coe 2,500 8,000,000 | 16,000,000 
IB, GOCE 2 — SA en oe 835 850,000 513,000 
EL Prondoe 6 WB OS Bi PEE ee ea er cLn eae ose | 19,000 | 87,000,000 | 146,000,000 
* Host plant, Trifoliwm repens. f 
, organism isolated as natural contamination of water from hydathodes of corn. 
