1913] ECKERSON—AFTER-RIPENING 293 
catalase increase up to a maximum, which is reached on the eighth 
day of germination (the hypocotyl is then 2.5 cm. long). Then 
the fats begin to break up and within two or three days disappear. 
The fats are transformed into a soluble substance of the character 
of a plant mucilage. This is later transformed into sugar, cellulose, 
and other substances. DELEANO says that the acids activating 
hydrolysis are formed during germination; he detected acetic and 
lactic acids. He thinks that catalase is directly concerned with 
hydrolysis of the fats. This is doubtful, however, since catalase 
is so universally present. Peroxidase reached a maximum about 
the fourteenth day of germination (the hypocotyls were 8.5 cm.). 
The chemical changes during the 90 days of after-ripening 
of Crataegus are the same as those of the first 8 days of germination 
of Ricinus. It is as though the chemical processes, telescoped 
in Ricinus, are drawn out in Crataegus. 
Seeds of the crab apple (Pyrus baccata) after-ripen in 30 days 
ats°C. At the beginning of their after-ripening period, hypocotyls 
of these embryos have an acidity and a water-holding power slightly 
greater than those of Crataegus after 60 days at 5° C. (hypo- 
cotyl 1.45 cc., N/2o KOH, moisture 48 per cent; cotyledons o. 368 
cc., moisture 39 per cent). Peroxidase increases gradually from a 
very little in the air-dry seeds to a considerable amount at germina- 
tion. As in Crataegus, oxidase does not appear in hypocotyls of 
Pyrus baccata until immediately before germination. 
EFFECT OF ACIDS 
FiscHER (11) finds that when seeds of water plants (Alisma, 
Sagittaria, and Sparganium) are treated with dilute solutions of 
acids, or the strong alkalies KOH and NaOH, the percentage of 
germination is increased. He conceives the H ions of the acids, 
and the OH ions of the alkalies as destroying the equilibrium of the 
cell and starting up the chemical processes.' Seeds treated with 
Solutions of the fatty acids (formic, acetic, propionic, and butyric) 
id not germinate. He therefore considers these acids toxic; 
but he used too concentrated solutions. In dilute solutions the 
* CROCKER has found’ that these seeds germinate readily if the coats are broken 
or removed. The protoplasm is not dorman 
