268 BOTANICAL GAZETTE [APRIL 
deficiency in seeds of Nicotiana Tabacum, Verbascum Thapsus, and 
Oenothera biennts. 
Substrata 
LEHMANN (30) reported increased germination in darkness of 
light-sensitive seeds such as Ranunculus sceleratus with soil as 
substratum. Baar (1) obtained an increased percentage of 
germination of seeds of Amaranthus when he substituted earth for 
filter paper as a substratum, but OTTENWALDER (40), who used soil 
and sand as well as filter paper as substrata for his Epilobium 
hirsutum seeds, found beneficial results in his experiments with 
only one lot of sand. Investigation showed that the sand had 
been treated with acid which had not been thoroughly washed out. 
TABLE XIII 
PERCENTAGE OF GERMINATION AFTER 18 DAYS 
ON sorL ON SAND In sort |IN SAND|ON FILTER PAPER 
SEEDS 
Light | Dark-| right | Dark- | right | Light | Light | Datk 
Verbascum Thapsus..... 40 34 30 20 + 2 24 41 3 
Daucus Carota.......... 56 28 54 28 33 58 63 19 
 cosracinper ova ee ee 2 ° 2 2 ° 6 3 2 
Rumex crisps. .......:. 68 2 46 Io 12 38 42 8 
Nicotiana Tabactim...... 70 6 78 ° 56 76 7I i 
In view of the divergent results with the different seeds, it was 
deemed desirable to determine the relation of sand and soil to 
germination in darkness of these light-sensitive seeds. Also the 
question arose as to whether light was as necessary under natural 
conditions as under laboratory conditions for the germination of 
light-sensitive seeds. The substrata were carefully sterilized, 
uniformly wetted, and prepared for the seeds. The seeds in 
“sand” and in ‘‘soil’? were buried to a depth of 0.25 inch. All 
were put under the same temperature conditions (23-26° C.). The 
results are shown in table XIII. The experiment was begun 
May 13 and closed June 1. 
The germination of seeds of Verbascum Thapsus on soil and sand 
in darkness is somewhat higher than that on filter paper. The 
substratum appears to have exerted a slightly favorable effect on 
the germination of seeds of Daucus Carota, but none on the other 
