926 



ADVENTURES IN RADIOISOTOPE RESEARCH 



female branch was fertilized on February 26th— 27th, the seeds being 

 collected on March 17th — 20th. A poor harvest was obtained, although 

 the number of seeds collected sufficed for the experiment. The comparison 

 of the activities of the seeds and the pollen by Mr. J. Ottesen led to 

 the following result. 



Fig. 2. Radioautograph of leaves 

 from aspen branch placed in a solution 

 containing 32p. 



(a) Determination carried out by Ottesen's micromethod.^^) 



No. of Dish 



I .. 



II .. 



Ill .. 



Weight of Seed Number of Seeds 

 4.91 mgm 110.0 



5.75 128.5 



4.27 95.5 



14.93 334.0 



Weight of pollen 1.07 mgm 



Average value 0.0230 ± 0.0005 



^1) J. Ottesen, Acta PMjsiol. Scand. 10, 201 (1945). 



