1913] ECKERSON—AFTER-RIPENING 201 
when the acidity has almost reached its maximum, the fats begin 
to break up and sugar appears. Oxidase first appears at this time. 
Hydrocyanic acid appears after 75 days, increases up to germina- 
tion, then decreases (19, 49). 
WATER-HOLDING POWER 
Since the hypocotyls of the air-dry seeds are basic, while the 
cotyledons are acid, it was thought that they might have less ability 
to take up water than the cotyledons. To test this, seeds were 
taken at different stages of after-ripening, the coats removed, and 
the naked embryos soaked in water for 5 hours. These were 
then dried carefully with filter paper and, after the hypocotyls 
were separated from the cotyledons, were put in separate 
weighing bottles. These were weighed, then heated in an oven 10 
minutes at 100° C., removed from the oven, and dried at 50° C. 
Many determihaticis were made. The accompanying table (II) 
gives a typical series. 
TABLE II 
WATER-HOLDING POWER OF EMBRYO OF CRATAEGUS GLORIOSA 
Hypocoryis COTYLEDONS 
, Wet Dry 
Percentage 4 = Percentage 
water weight pe “ water. 
Wet Dry 
weight weight 
grams grams 
Coats removed and soaked 
Ste 0.0157 | 0.0121 23 0.2690 | 0.1542 42 
90 ‘ays ae Co 0.0189 | 0.0116 | 38 | 0.2700] 0.1744| 35 
Germinated (hyp. 3mm.)..| 0.0289 | 0.0115 60 0.2094 | 0.1260 39 
ACIDITY 
Determinations of acidity were made at the same periods o 
after-ripening as the water determinations (table III). ae 
embryos were washed in distilled water which had been boiled 
to expel CO,,. 
It will be seen that the metabolism of the fats does not begin 
until the acidity has reached a certain amount, the water content 
has increased greatly, and the enzymes are set free. The hypocotyl 
does not elongate until that time. It has long been known that 
