696 



SCIENCE 



[N. S. Vol. XXXIII. No. 853 



cation that came to light our authors had some 

 difficulty in placing, finding it hard to decide 

 whether it helonged to the dicotyledons or 

 monocotyledons, but as a final conclusion they 

 say : " On the whole, judging from its detailed 

 structure and general appearance, we incline 

 to place the flower in the Liliacess." Is it to 

 be presumed that such adumbrations as the 

 above add much to the evolutionary history of 

 the Liliacese, or of the monocotyledons in 

 general ? 



It is not necessary to further mention the 

 technical portion of the paper, and it only re- 

 mains to call attention to some of the nomen- 

 clatorial anomalies. All the genera and 

 species published as new to science in the pres- 

 ent paper were printed a year earlier in the 

 Geological Magazine, London, N. S., Vol. 6, 

 1909, pp. 557-559, but without characteriza- 

 tion. They are all again listed on page 1 of 

 the paper under review, some of them inci- 

 dentally mentioned at various places in the 

 introduction, each again appearing at the 

 head of the section of the text in which it is 

 described, while at the end of the description 

 there is a formal generic and specific charac- 

 terization where each is called " gen. nov.," or 

 " sp. nov." The question arises as to how 

 these shall be cited. To give Gryptomeriopsis 

 as a concrete example : Shall we quote page 1 

 of this paper, where it is first printed; page 3, 

 where it is mentioned and partially described; 

 page 52, where it stands at the head of the de- 

 scription; or page 57, where the genus and 

 species are formally dedicated? 



The reviewer does not wish to be understood 

 as in any way underestimating the value of 

 histology in establishing a firm basis on which 

 to work out the developmental history of 

 plants, but if the study of the internal struc- 

 ture of fossil plants, as contrasted with the 

 study of plant impressions, is to be given 

 proper weight it must be subject to the same 

 scrutiny. If the study of the intimate anat- 

 omy of fossil plants leads only to indefinite- 

 ness and ineonclusion, it is not entitled to 

 greater weight than attaches to the study of 

 the impressions of plants. 



F. H. Knowlton 



' SOME RECENT ADVANCES IN FLV0BE8- 

 CENCE AND PHOSPEOBESCENCE'^ 

 After an opening period of great activity, 

 which began with Becquerel, Herschel and 

 Stokes and included the important work of 

 Lommel, Wiedemann and Schmidt and of nu- 

 merous other physicists, there was a long time 

 of comparative quiescence during which 

 luminescence, to use the word proposed by E. 

 Wiedemann, was a neglected branch of optics. 

 Quite recently there has been renewed activity 

 in this field and it is of some aspects of this 

 newer work that I shall try to give a brief ac- 

 count. No approach to a complete summary 

 can be made in a single paper and I shall deal 

 chiefly with certain investigations which are 

 particularly suggestive of the beginnings of 

 correlation in this involved and obscure por- 

 tion of the science of radiation. 



The Relations of Phosphorescence to Fluo- 

 rescence. — The common view that phosphores- 

 cence is simply what remains of fluorescence 

 after the cessation of excitation would seem to 

 need essential modification according to the 

 latest paper of Lenard,^ who, after extending 

 his observations to some fifty phosphorescent 

 compounds, made by the addition of a trace of 

 some metallic salt to a sulphide of strontium, 

 barium or calcium and certain heat treatment 

 with a flux, considers that it is necessary to 

 distinguish two phenomena, the one tempo- 

 rary, which ceases almost instantly after the 

 end of excitation {Momentan-process), and the 

 phenomenon of long-time phosphorescence 

 {Bauer-process) . The distinction is three 

 fold : The momentary process may be produced 

 independently of the other (1) by very brief 

 excitation; (2) it may be excited by the use of 

 portions of the ultra-violet spectrum which are 

 incapable of producing long time phospho- 

 rescence or (3) at temperatures above or be- 

 low the range within which long-time phospho- 



' Abstract of a paper presented before Section 

 B at the Minneapolis meeting of the American 

 Association for the Advancement of Science. 



-Lenard, Annalen der Physik (4), Vol. XXXI., 

 p. 641, 1910. 



