228 The American Naturalist. [March, 



with an alcoholic solution derived from grass leaves. Two beakers 

 were filled with this green solution and placed in tin chambers with 

 blackened inner walls but having on one side a quadrangular opening 

 with strongly projecting edges for the entrance of light. In front of 

 each opening was placed a parallel walled glass vessel 196 millimeters 

 high, 93.5 mm. wide and 40 mm. thick. Into one of these vessels red 

 beet juice was poured and into the other white beet juice, both filtered 

 and of the same specific gravity. The result was decisive. The light 

 which passed through the anthocyan solution discolored the chlorophyll 

 much less rapidly than that which passed through the colorless solution. 

 (2) Does anthocyan convert the light rays into heat rays ? Experiments 

 were made with the foliage of green and red leaved varieties of the fol- 

 lowing species, viz. Fagus sylvatica, Corylus avellana, Berberis vulgaris, 

 Acer platanoides, Brassica oleracea, Dracama ferrea, Canna indica; with 

 decoctions of white and red beets ; and with the petals of a white and 

 a red rose. Exactly weighed quantities of the leaves, etc., were placed 

 in the parallel walled glass vessels already mentioned, thermometers 

 were then plunged into the center of the mass, and the vessels were ex- 

 posed to the action of direct sunlight filtered through a nearly saturated 

 alum water screen 4 cm. thick (to absorb the heat rays). In most of 

 the species (Dracaena ferrea and Carina indica gave contradictory 

 results) the ability of anthocyan to convert light rays into heat rays 

 seems to have been demonstrated conclusively. In one to two minutes 

 in favorable cases there was a rise of temperature in the vessels contain- 

 ing the red leaves, the maximum difference amounting to as much as 

 4°C. As soon as the sun was covered by a cloud there was a notice- 

 able fall of temperature in both vessels, and when the cloudiness lasted 

 10 to 20 minutes the temperature became the same or nearly the same 

 in both vessels. Subsequently an effort was made to determine whether 

 the different light rays of the solar spectrum behaved differently. For 

 this purpose three vessels containing, in turn, red leaves of several species 

 of plants were exposed to direct light under the following conditions ; 

 the light entering one vessel was filtered through the alum solution, that 

 entering another was filtered through a screen of sulfuric-copper- oxide- 

 ammonia, that entering the third was passed through a solution of bi- 

 chromate of potash, it having been determined in advance spectrosco- 

 pically that the two colored screens divided the spectrum in about the 

 middle of the green. Under these conditions the rise of temperature 

 was less behind the blue screen than behind the orange one, and less 

 behind the latter than behind the alum screen. A consideration of the 

 third supposed function of anthocyan is left by Dr. Kuy for a subse- 

 quent paper. — Erwin F. Smith. 



