322 



SCIENCE 



[N. S. Vol. XLIII. No. 1105 



ing the direction of an Acoustical Kay," by A. G. 

 Webster. 



"The Propagation of Transverse Waves in a 

 Bar," by Louis Thompson. 



"The Exceptions to the Law of Dulong and 

 Petit, " by J. E. Siebel. 



"Experiments with Slow Positive Bays," by A. 

 G. Dempster. 



"Theory of the Free Vibrations of a Lecher 

 System," by F. C. Blake. 



"Springs of Minimum Weight," by Henry C. 

 Lord. (By title.) 



"Spectra of Some Halogen Compounds and 

 Phenomena Connected Therewith, ' ' by Charles 

 Sheard and C. S. Morris. 



"On a New Method of using the Reversible 

 Pendulum for the Determination of g," by J. C. 

 Shedd. 



' ' The Effect of Absorbed Gases in Photoelec- 

 tric Emission," by Robert J. Piersol. (Read by 

 E. P. Lewis.) 



At the special session in charge of Section B on 

 Wednesday afternoon the following program was 

 presented: 



"The Dependence of Progress in Science upon 

 the Development of Instruments" (Vice-presi- 

 dential address before Section B), by Anthony 

 Zeleny. 



"A General Survey of the Field of High Pres- 

 sure," by P. W. Bridgman. Discussion by A. G. 

 Webster. 



The Northrup Visible Molecules Apparatus was 

 demonstrated at the close of the session. 



At a short busiaess session on Wednesday the 

 result of the mail ballot for officers for 1916 was 

 announced as follows: for president, R. A. Milli- 

 kan, of Chicago; vice-president, H. A. Bumstead, 

 of New Haven; secretary, A. D. Cole, of Colum- 

 bus; treasurer, J. S. Ames, of Baltimore; mem- 

 bers of council, Irving Langmuir, of Schenectady 

 and G. B. Pegram, of New York; members of edi- 

 torial board, A. Trowbridge, E. P. Lewis and W. 

 C. Sabine. Several other items of business were 

 transacted. 



The registration for the meeting was 158. 

 About one hundred were present at the Physicists ' 

 dinner on Wednesday evening. Whether judged 

 by the number and character of the papers pre- 

 sented, by the attendance or by the amount and 

 interest of the discussion following the papers, 

 this meeting was one of the best that the Ameri- 

 can Physical Society has ever held. 



A. D. Cole, 

 Secretary 



THE BOTANICAL SOCIETY OF 

 AMERICA. II 



The Evolution of Beprodiiotive Mechanisms in 

 Seed Plants: E. C. Jeffrey and R. E. Torrey. 

 Mechanisms strictly so called are not numerous 

 in plants. Among them may be classed the an- 

 nulus which causes the opening of the sporangium 

 in ferns and fern allies, including the cycads. 

 The annulus is obviously a structure of epidermal 

 origin, sometimes showing the presence of stomata. 

 In the seed plants from Ginkgo upwards the open- 

 ing mechanism of sporangia is not primarily of 

 this nature. In the lower Gymnosperms the cryp- 

 togamic wood of centripetal development persists 

 strongly, clearly indicating their filiation with the 

 fern series. In the higher Gymnosperms the cen- 

 tripetal or eryptogamic wood becomes merged in 

 the so-called transfusion tissue. The purpose of 

 the present communication is to make clear that 

 the transfusion tissue of Ginkgo and the Abie- 

 tineae obviously furnishes the mechanism for open- 

 ing the microsporangium. In the higher Conifers 

 as well as in the Gnetales and angiosperms the 

 fiber layer or mechanical system of the anther wall 

 is no longer related to the fibrovascular system. 

 The considerations advanced make it clear that 

 sporangial mechanisms are of diverse origins. In 

 the Cycadales and their allies the fern-like plants, 

 the epidermis supplies the mechanically active 

 layer. From the Ginkgoales upwards the tissues 

 of the fibrovascular system, particularly the ves- 

 tiges of the eryptogamic centripetal wood known 

 as transfusion tissue, take on the function of pro- 

 viding for the opening of the spore sacks. The 

 sporangium of the lower forms may appropriately 

 be designated ectokinetic since its action depends 

 upon the mechanical action of an external tissue, 

 the epidermis. The sporangium of the higher 

 forms, in which the fibrovascular tissue is primi- 

 tively related to the mechanically active layer, is 

 appropriately designated endokinetic. 

 Th-e Comparative Rapidity of Evolution in Various 

 Plant Types: Edmund W. Sinnott. 

 Given an equal degree of heritable variability, 

 the rapidity with which a plant undergoes evolu- 

 tionary change depends on the growth-type to 

 which it conforms. Herbs, with their very brief 

 period from seed to seed, accumulate changes much 

 more quickly than do trees and shrubs, with their 

 much longer generations. Local specific and 

 generic types therefore arise most readily among 

 herbs. Herbs occur in a much smaller number of 



