178 LIVING PLAKTvS 



rived from the tannins. The colors which 

 attract animals belong chiefly to this group. 



Several theories have been proposed in the 

 last decade to account for the functions of 

 Relation of an- anthoc^^an. Engelmann found that red pig- 

 thocyan to light jjient permits 90 per cent of the orange rays, 

 10 to 30 per cent of the green and yellow, 50 

 per cent of the blue and 80 per cent of the 

 violet to be transmitted unchanged. Miiller 

 has plotted the absorption spectrum of a large 

 number of anthocyans, with the result that 

 while Engelmann's results hold good in the 

 main, some also absorb the lower red rays. 

 As a natural result of such physical character- 

 istics it is found that anthocyan converts 

 light into heat, a portion of the converted light 

 being the disintegrating rays of the blue violet 

 end of the spectrum . That the anthocyan does 

 partially retard the disintegration of chlor- 

 ophyll by light may be seen if two vessels con- 

 taining solutions of chlorophyll are so ar- 

 ranged that the light which strikes on one of 

 them shall first pass through a parallel- walled 

 vessel containing water, and that which 

 strikes the other through a similar vessel con- 

 taining a solution of anthocyan. The chlor- 

 oph341 in the first will soon become much more 

 discolored than in the second, which has re- 

 ceived light transmitted through anthocyan. 

 That the disintegrating rays may be convert- 



