98 GROWTH OF PLANTS 



of dispersion of the stored fat; (5) decrease in the amount of stored fat 

 and protein, with an increase of sugar content and the first appearance 

 of starch; (6) the translocation of food in the form of fat or fatty acids 

 from endosperm to embryo; (7) a seven-fold increase in the amino acid 

 content, and a complete disappearance of histidine from the endosperm; 



IS 



13 



>- 

 t 



< 



UJ 



>- 



N 



Z 

 u 



Lipase 

 Peroxidase 



5 7 9 



WEEKS AT LOW TEMPERATURE 



FiGTJKE 34. Catalase, peroxidase, and lipase activity of embryos of Rhodotypos kerri- 

 oides after various weeks in moist peat moss at 5° and 10° C (41° and 50° F) alternated 

 weekly. The activities are calculated on the basis of the activity of the control expressed 

 as one. 



(8) an increase of soluble proteins with a marked hydrolysis of the stored 

 proteins; (9) slight growth of embryo; (10) very slight increase of the 

 respiration intensity; (11) increased respiratory quotient; (12) decreased 

 intramolecular respiration; (13) a doubling of the catalase activity; and 

 (14) the rise in vigor of seeds as sho\vn by their resistance to fungal attack." 



A later study of J. scopulorum seeds by Afanasiev and Cress ^ confirms 

 many of the results found by Pack and shows that removal of the fruit 

 and seed coats hastens the after-ripening of the seed in low-temperature 

 stratification. 



Flemion ^^' p-^^^ summarizes the chemical and physiological changes oc- 

 curring in Rhodotypos embryos during after-ripening as follows: "Analyses 

 of the seeds at intervals of two weeks during the after-ripening period 

 show that the seeds increase in catalase, peroxidase, and lipase activity 

 and also increase in water absorption power, nitrogen-soluble in 80 per 

 cent alcohol, titrable acid, and sucrose. The ether-soluble fraction de- 



