^94 ANNUAL REPOET SMITHSONIAN INSTITUnON, 19i5. 



water, 50 per cent potassium hydroxide, and 5 per cent hydrochloric 

 acid. 



To determine the fluorescing power in the wood of Pteroearpus 

 indicus and P. dalhergioides^ pieces of each of known weight were 

 treated with hot absolute alcohol. On the addition of a few drops 

 of alkali, fluorescence was shown in each extract. The process 

 was continued until fluorescence could no longer be detected by means 

 of the fluorescence lamp. After the alcohol extraction was com- 

 pleted, the same samples were boiled in water until no further 

 fluorescence could ho. observed. The results demonstrated the fact 

 that stronger fluorescence was displayed by the aqueous extracts, 

 indicating either that the fluorescing substances are more easily 

 soluble in water than in alcohol or that probabl}' some of the fluor- 

 escing substances present are soluble only in water and not in 

 alcohol. 



In all cases fluorescence was observed, by means of the fluorescence 

 lamp, in dilutions less than one to one hundred thousand parts, 

 except in the sapwood of Pterocarpus dalhergioides^ which yielded 

 only a weak fluorescence in the aqueous extract. In the heartwood 

 of this species the bright red portions show only slightly stronger 

 fluorescence than the sapwood, while the paler streaks show the 

 strongest fluorescence of all. 



The Philippine narra, Pterocarpus indicus^ shows a much stronger 

 fluorescence than any part of the Andaman redwood, as the writer 

 has already stated; but not so strong as the Mexican lignum nephriti- 

 cum, Eysenhardtia polystachya of equal dilution. 



Dry wood sections showed no fluoresage when observed in the 

 fluorescence microscope. After mounting them in borax glycerine, a 

 greenish veil of diffused light was observed. There w^as no evidence 

 that the colored bodies showed a stronger fluorescence. In fact, the 

 fluorescence could still be observed in sections where the colored 

 bodies were almost entirely removed, as in the red heartwood, and 

 where the color bodies are very scarce, as in the light sapwood. It 

 is therefore believed that the red colored bodies are not the cause 

 for the fluorescence. 



FRUITS OF PHILIPPINE PTEROCARPUS. 



Pterocarpus Blancoi is very closely related to P. indicus^ as Mr. 

 Merrill has already pointed out, diff'ering from it chiefly in its larger 

 pods and its relatively narrower leaflets. Pterocarpus echinatus 

 Pers., which also occurs in the Philippines is distinguished by its 

 prickly pods, and its leaflets are sometimes long-acuminate. It was 

 mistaken by Vidal for Pterocarpus erinaceus Poir., an African 



