1921] GARDNER—GERMINATION 269 
seeds. Such results suggest a beneficial effect on some particular 
constituent contained only in seeds of Verbascum Thapsus. In light 
the percentage of germination seems to correspond roughly to the 
light intensity. Where the lighting is good, as on the filter paper 
or sand, the germination is good. Where it is diminished, as in 
the case of seeds buried in sand or soil, the germination is reduced. 
The increase of germination of seeds on sand or soil in darkness 
may be referred largely to the action of constituents of the soil 
and sand. The low germination of seeds of Oenothera biennis 
may be due to periodicity in dormancy, since seeds from the same 
lot gave a germination of 78 per cent in light and o per cent in 
darkness in October. From these results it appears that constitu- 
ents of soil may only partially substitute for light with some seeds 
and not at all with others. 
Effects of electrolytes 
The effects of electrolytes on the germination of light-sensitive 
seeds have been variously reported. Beneficial effects on germina- 
tion in darkness of Ranunculus sceleratus from hot water extracts 
of soils, Knop’s nutrient solution, and salt solutions have been 
reported by LEHMANN (30). He reported no benefit from cold 
water extracts of soils. LEHMANN and OTTENWALDER (36) found 
that weak acid solutions promote germination in darkness of 
seeds of Verbascum Thapsus, V. thapsiforme, and Lythrum Salicaria. 
OTTENWALDER (40) reported that acids promote the germination of 
seeds of Epilobium hirsutum in darkness. GASSNER (15) reported 
that nitrogen compounds such as nitrates, nitrites, and ammonium 
salts through a wide range of concentrations favor the germination 
of seeds of Chloris ciliata in darkness. As many of the electrolytes 
reported by these investigators belonged to the lyophobe or 
lyophile series, a systematic study of their effects was undertaken, 
to discover, if possible, some relation between electrolytes and germi- 
nation. Lots of 100 seeds each were counted into test tubes, about 
2 cc. of a solution of an electrolyte added, and the tubes placed in 
darkness. After 24 hours most of the solution, was drained from 
each test tube, which was promptly returned to the dark chamber 
for the seeds to germinate. The period allowed for germination 
was 7 days after soaking. The results are given in table XI 
