"4 
4 
; 
1913] ECKERSON—AFTER-RIPENING 297. 
lt is evident that there is a correlation between acidity of the 
hypocotyl of Crataegus, its water-absorbing power, production of 
enzymes, and germinating power. Whether the acidity is causal or 
merely correlative is not known. There is some evidence, how- 
ever, that it is causal. GREEN (17, 18) has shown that it leads to 
the liberation of enzymes; and MartTIN FIscHER (12) that it 
increases the water-absorbing power of colloids. Other dormant 
seeds of the Rosaceae are now being studied with the hope of 
gaining further knowledge on this point. 
Acknowledgments are due Dr. WILLIAM CROCKER, under whose 
direction the work was done. 
UNIVERSITY oF CHICAGO 
LITERATURE CITED 
I. APPLEMAN, CHARLES O., Physiological behavior of enzyme and carbo- 
hydrate transformations in after-ripening of the potato tuber. Bor. 
GAZ. 52:306-315. 1911. 
- Bos, H., Wirkung galvanischer Stréme auf Pflanzen in der Ruheperiode. 
Biol. Centralbl. 27:673-681, 705-716. 1907. 
4s. CHRISTENSEN, P., Chemical researches of bulbs in the later phases of the 
resting period. Bull. Acad. Roy. Danemark (Copenhague). pp. 44. 1908. 
x 4. CROCKER, eS Réle of seed coats in delayed germination. Bor. 
GAZ. 42: 265-201. 
5- ———, Longevity of seeds. Bor. Gaz. 47:69-72. 1900. 
“16. Davis, Witmer E., and Rose, R. CaTtin, The effect of external conditions 
Prats the siteceestag of the seeds of Crataegus mollis. Bot. Gaz. 54: 
Igt2. 
: oo NT; a chemiques sur la germination. Centralbl. 
Bakt. 24?:130-147. 
8. Enzyklopidie der rilkermkopinchen Technik. II. Vitale Firbung. pp. 589- 
602. 1910 
9. Faurt-Fremtet, E. , Les mitochondries des Protozaires et cellules sexuelles. 
Arch. Anat. Mic. 11: 457-648. Igt0. 
10. Fawcet, H. S., Viability of weed seeds under different conditions of 
treatment and study of their dormant periods. Proc. Iowa Acad. 
N 
~~ 
1908. 
II. Fischer, ALFRED, Wasserstoff- und Hydroxylionen als Keimungsreize. 
Ber. Deutsch. Bot. Gesell. 25: 108-122. 1907. 
12. FIscHER, Martin, Edema; a study of the physiology and the pathology 
of water absorption by the he organism. New bag IgIo. 
