KEi\i\ETH I . TH/MANN AND i.EORGE M. CURRY G55 



.600 



.500 



.400 



V) 

 UJ 



o 



-J 

 < 

 o 



o 



,300 



.200 



.100 



\ 



V 



\ 

 \ 





Jk-L 



\ 



340 



420 



500 



580 



660 



740 780 



WAVE LENGTH 



Fig. 6. Absorption spectrum in vivo of 20 Avena coleoptile tips determined witli 

 the opaque plate method. Below, curve corrected for end-absorption. 



not shifted from those in the extract. Unfortunately, the end-absorp- 

 tion obscures the important range in the near ultraviolet. 



In 1937, and again in 1955, Biinning demonstrated the presence of 

 carotene or a lutein in the coleoptile by the microchemical method 

 of Molisch, ^vhich leads to the formation of characteristically shaped 

 crystals in situ. He found a high concentration of the carotenoid 



