6 BOTANICAL GAZETTE [JULY 
Investigation 
The material studied was as follows: 
Seeds ar of crop Time of collection 
Amaranthus retroflexus 1919 August 2-September 7, 1919 
Chenopodium album 1918 January 29, 1919 
Rumex crispus 1919 ©63—Ss-—s August 1919 
Crataegus IQI7 October 1917 
In addition, seeds of Prunus pumila (from Mineral Springs, Indiana), 
and of P. persica, P. armeniaca, P. Cerasus var. Morella, P. do- 
mestica var. Blue Gage, and the red Burbank plum, obtained in the 
market, were also studied. All rosaceous seeds except Crataegus 
were freed at once from pulp, dried, and in most cases opened and 
used immediately. Amaranthus and Chenopodium seeds were 
stored at room temperature until used. Seeds of Crataegus were left 
at room temperature until they were scanint from the carpels, 
when they were placed at once under g ditions at 10°C. 
In preparation for an experiment the seeds were pce in 
distilled water and left in the refrigerator at approximately 10° C. 
for twenty-four hours. Cotton and filter paper were placed in 
Petri dishes and the whole sterilized in an electric oven. Before 
being used, the cotton was saturated with sterile distilled water. 
The seeds were thoroughly shaken in several portions of sterile 
water, and were either used at once or placed in the Petri dishes 
and stored in the refrigerator until needed, in order to avoid the 
influence on respiration of variations of temperature. By means 
of these precautions it was possible, to a very great extent, to pre- 
vent infection of the seeds with molds or bacteria, and at the same 
time to avoid the modification of respiration due to treatment with 
disinfectants (36, 38, 42). The amount of material used depended 
largely upon the size of the seed and of the apparatus. For 
Amaranthus and Chenopodium, 1 gm. of air-dry seeds was the usual 
amount, a weight representing approximately tooo seeds. Cor- 
responding numbers and weights for the other seeds were: 
Seed Number | Weight (gm.) 
MU CON 0.5 
us i 2 0.7 1.00 
Prunus domestica 2 0.7 -0.8 
us armeniaca I 0.8+ 
Prunus Cerasus 10 0.8 
Prunus pumila I 0.8 
