September 11, 1896.] 



SCIENCE. 



351 



gests that the color layers act as a screen for 

 the conversion of light into heat, useful not 

 only in the trans-location of the carbohy- 

 drates, but also in all metabolic processes. 

 Such a use is subserved in alpine plants; in 

 those of eastern North America, in which 

 the climatic conditions are alpine; in the 

 pistils of anemophilous plants, to promote 

 the growth of pollen tubes; in extra floral 

 nectaries, to accelerate the metabolism of 

 the carbohydrates, and in many adapta- 

 tions in the Cryptogams. 



Seasoning from the fact that a large 

 number of plants growing in shady moist 

 situations, and in the tropics where the air 

 is much warmer than the leaves, are pro- 

 vided with erythrophyll, absent from speci- 

 mens under the opposite conditions, he 

 substantiates and extends the idea of 

 Kerner that the color in these instances is 

 a device for promoting transpiration. 



Further, the colors of young shoots and 

 leaves act in the same manner, and, by in- 

 creasing the amount of water conducted to 

 these parts, secure a greater supply of 

 nutritive salts. 



It is but proper to say, however, that 

 this method of reasoning does not explain 

 in any adequate manner the autumnal 

 colors, nor of course the occurrence of 

 colors in external hairs, or in the internal 

 tissues, where no relation, or no useful re- 

 lation, to light can exist. 



By far the most interesting portion of 

 the paper is that in which the results of 

 the investigation upon the whitish or silvery 

 patches due to air cavities underneath the 

 epidermis of leaves of Begonia, Dracaena, 

 etc. It was found that if the under side 

 of such leaves were coated with some sub- 

 stance easily melted, such as cocoa butter, 

 and the upper side exposed to light or heat, 

 the portions of the leaf under the silvery 

 areas were less easily heated, and conse- 

 quently less easily cooled, than the neigh- 

 boring green areas. 



This device retards chlorophyll action, 

 but under the cool, damp conditions in 

 which such plants are found it promotes 

 transpiration by preserving a temperature 

 higher than the surrounding atmosphere. 



The velvety appearance of many leaves 

 is found to be due to the papillose extension 

 of the epidermal cells in such form as to 

 act as lenses in entrapping rays of light or 

 heat striking the surface at any angle, thus 

 securing an additional aid to transpiration. 



The chief results of the paper may be 

 summarized as follows : The existence of 

 ' warning ' colors is not proven ; the con- 

 clusion of Pick that leaf-red converts light 

 into heat, useful in translocation of carbo- 

 hydrates, is broadened to include the gen- 

 eral metabolism of the plant in its applica- 

 tion ; the ' protection ' theory of leaf-red by 

 Kerner is refuted in great part ; the con- 

 clusions of Kerner as to the uses of leaf-red 

 as a means of promotion of transpiration are 

 extended and substantiated; and the silvery 

 white as well as the ' velvety ' appearance 

 of many leaves are to be regarded as means 

 for the promotion of transpiration under 

 different circumstances. 



D. T. MacDougal. 

 Minneapolis, Minn. 



CURRENT NOTES ON ANTHROPOLOGY. 

 MORTUARY CEREMONIES. 



Properly studied, the mortuary cere- 

 monies of tribes offer one of the most pro- 

 ductive fields of ethnologic research. A 

 valuable contribution to this branch has 

 lately appeared in Dr. W. Caland's Die 

 Altindischen Todten- und Bestattungsgebrdiiche 

 (pp. 191, J. Miiller, Amsterdam, 1896). 

 Its investigations are based on a close col- 

 lation of the rituals for the dead in the 

 various Vedas and other sources, a num- 

 ber of them still in manuscript. The earlier 

 researches of Colebrooke, Wilson, Max 

 Miiller and others have been considered, 

 and extensive additions to their studies are 



