1921] GARDNER—GERMINATION 279 
reaction of the substratum after a period of incubation might 
throw some light on what was happening in the seeds. A small 
quantity of each kind of seed was soaked in distilled water, 
0.01 N NH,NO, solution, and 0.01 N NaNO, solution at room 
temperature, and the substratum tested for reaction with neutral 
red. The results are shown in table XVIII. 
TABLE XVIII 
SOAKED 18 HOURS IN | SOAKED 24 HOURS IN | SOAKED 24 HOURS IN 
DISTILLED WATER o.or N NH,NO, o,orN NaNO; 
SEEDS 
Light Darkness Light Darkness Light Darkness 
M kevin sete APU Alkaline | Alkaline |Alkaline | Alkaline | Alkaline | Alkaline 
Rumex crispas... 2. 2... Acid cid Acid Aci Aci Acid 
Benes se teal St ages Nee Alkaline |Alkaline |Alkaline |Alkaline | Alkaline |Alkaline 
Oenothera biennis........ Neutral |Neutral |Alkaline |Neutral |Alkaline |Neutral 
Nicotians Tabactie... 166, 454. Alkaline |Alkaline | Alkaline | Alkaline 
From the results it appears that seeds of Verbascum Thapsus, 
Daucus Carota, and Nicotiana Tabacum excrete an alkaline sub- 
stance in darkness as well as in light; that seeds of Rumex crispus 
excrete an acid substance in darkness as well as in light; and that 
seeds of Oenothera biennis excrete an alkaline substance in light. 
A quantitative experiment also verifies a part of these results. 
Weighed quantities of each of the five kinds of seeds were incubated 
in light for five days in tubes containing 2 cc. of o.or N NaNO, 
respectively. The results are given in table XIX. 
TABLE XIX 
Seeds Weight of seeds (gm.) Required to titrate 
Me agers en Se ee tn ae 0.7406 1.0 cc, 0.01 N HCl 
Rumex crispus....... Pale a Cay 1.3385 1.5 cc. 0.01 N NaOH 
Daucus Ca i RS eee yin ee 0.6510 0.9 cc. 0.01 N HCl 
Oenothera biennis................ 0.7580 0.5 cc. 0.01 N HCl 
Nicotiana Tabacum....... Lies 0.8403 1.8 cc. 0.01 N HCl 
The longer period of incubation evidently allowed time for 
the excretion of a measurable amount of acid or base by each kind 
of seed. From these results it appears that seeds of Rumex crispus 
excrete measurable amounts of acid substance during incubation, 
while the other kinds excrete alkaline substances. 
