30 



THE VITALITY AND GEKMINATION OF SEEDS. 



9 



the opening in the top of the incubator. The priniavv object of the 

 tubes was to prevent an}' water vapor from escaping within the incu- 

 bator and thereby doing damage to the seeds that were to be kept dry 



in the same incubator. For the same reason 

 tlie corli in the jar was well coated with paraf- 

 fin. Approximate!}' the same volume of water 

 was maintained in the jar throughout the ex- 

 periment, more water being added through 

 tube rt, as occasion demanded, to replace the 

 loss by evaporation. The chief advantage in 

 having two tubes was the comj^arative ease 

 with which the air within could be displaced 

 b}' a fresh suppl}' by forcing a current of fresh 

 air through one or the other of the tubes. 



Two such preparations were made, one being 

 left in the oven maintained at a temperature 

 varying from 30^ to 32^ 

 C. , the other in the oven 

 maintained at a tempera 

 ture varying from 36° 

 to 37^ C. In both cases 

 the bottles contained 

 five packages of each of 

 the five samples of seed, 

 thus making provisions 

 for testing at different 

 intervals. 



In order to suppl}' the 

 conditions for the second 

 method of treatment, 

 similar packages from the same samples of seeds 

 were put into 8-ounce bottles, which were then 

 kept for five days in a moist chamber. The in- 

 crease in weight due to the absorption of water 

 within the five days was as follows: Beans, 3.03 

 per cent; cabbage, 8.09 per cent; carrot, 8.26 per 

 cent: lettuce, 7.45 per cent, and onion 8.43 per 

 cent. This increase, with the water already 

 present in the air-dried seeds, gave a water con- 

 tent of 13.23 per cent for the beans, 13.9i> per 

 cent for the cabbage, 13.60 per cent for the carrot, 

 12.45 per cent for the lettuce, and 14.84 per cent 

 for the onion. 



The bottles were then corked and sealed with paraflUn, but were so 



Fig. 1. — Apparatus used to de- 

 termine the effect of moisture 

 and temperature on the vitality 

 of seeds in communication with 

 free air. 



Fig. 2. — Apparatus u.sed to 

 determine the effect of mois- 

 ture and temperature on the 

 vitality of seeds not in com- 

 munication with free air. 



