56 



BOTANICAL GAZETTE 



[JANUARY 



the maximum, optimum, and minimum temperatures for chloro- 

 phyll formation in the seedlings being represented by temperatures 

 somewhat below 30, 15, and somewhat above o° C. 



Seedlings grown at 0=1= i° C. developed anthocyanin, while those 

 grown at 30 C. developed xanthophyll. When cultures at o± i° C. 

 were supplied with glucose they developed more anthocyanin. 

 The seedlings grown at 30 C. were made to develop anthocyanin 

 by the addition of glucose. From the foregoing it appears that 

 the seedlings form various pigments according to their reserve sugar 



TABLE XXII 



Effect of light and temperature on development of chlorophyll* 



♦Average of 50 trials. 



supply. Seedlings with little sugar tend to develop xanthophyll, 

 those with more sugar chlorophyll, and those with an abundance 

 of sugar anthocyanin. 



Practical application. — The foregoing experiments make it 

 possible to devise an outline for the practical production of juniper 

 plants. This should be of interest to growers, since it has furnished 

 a means of increasing many fold the percentage of germination and 

 of developed seedlings. After collection, the seeds are freed from 

 the berries, sorted, and sterilized as has been described. The seeds 

 are then put into Petri dishes or covered flat vessels on filter paper 

 supported by wet cotton. These vessels of seeds are kept at a 

 constant temperature of about 5 C. (41 F.) for after-ripening, 

 which takes about 100 days. This after-ripening period can be 

 shortened 10 days by drying slightly and moistening again the 

 seeds at about the forty-fifth day. When the coats have split 



