298 ANNUAL REPORT SMITHSONIAN INSTITUTION^ 1915. 



or no fluorescence, while that of the pale variety yields a distinct 

 fluorescence. 



Authors have hitherto tried to trace lignum nephriticum to some 

 one source. Dr. Otto Stapf, after a careful study of the history of 

 the wood and experiments upon a specimen of " cuatl " from the 

 Mexican collection in the Paris exposition, was convinced that the 

 mother plant of lignum nephriticum is Eysenhardtia amorj)hoides. 

 Dr. Plans- Jacob Moller of Copenhagen after an equally exhaustive 

 study was confident that the source of lignum nephriticum was not 

 Eysenhardtia but a Mexican tree belonging to the genus Ptero- 

 carpus. It was assumed by Dr. Stapf that both the reddish yaluni 

 indiamiin of which Johan Bauhin's historical cup was made and 

 the " white " wood yielding an infusion like pure colorless spring 

 water of which Kircher's cup was made were identical with the 

 dark-colored wood used by Robert Boyle in his study of fluorescence. 

 The erroneous conclusion would necessarily follow that the logs 

 which Hernandez described as " larger than very large trees " were 

 those of Eysenhardtia, although, it is quite certain that this genus 

 includes only shrubs and small trees. On the other hand Moller 

 endeavors to make Hernandez's description of coatlU with its tiny 

 leaflets suggesting the foliage of the chick-pea or common rue, apply 

 to the genus Pterocarpus, of which all the known species have large 

 leaflets in no way comparable to those of the plants mentioned.^ 

 In the present paper the twO' distinct sources of the woods called 

 lignum nephriticum are for the first time definitely indicated, the 

 fluorescence phenomena displayed by infusions of each described and 

 illustrated, and the origin of the celebrated cups of Kircher and 

 Bauhin traced to the country where they were made. 



1 See Science, n. s. 43: 432, March 24, 1916. 



