SCIENCE 



Friday, December 7, 1917 



CONTENTS 



The Chemical Basis of Axial Polarity in Me- 

 generation : Dr. Jacques Loeb 547 



Comments on the Theories of the Structure of 

 Matter: Drs. K. George Falk and J. M. 

 Nelson 551 



The FossibiUty of using Gravity Anomalies in 

 the Searcli for Salt-dome Oil and Gas Pools: 

 Eugene Wesley ShjVw 553 



Field Trip of the American Association of 

 State Geologists: W. O. Hotchkiss 556 



Scientific Events: — 



The Late- Dr. Richard Weil; Medical In- 

 spection of Camp Wheeler; the Use of the 

 McKay Bequest to Harvard University; 

 Annual Meeting of the American Ornith- 

 ologists' Union; General Announcement of 

 the Permanent Secretary of the American 

 Association for the Advancement of Science. 557 



Scientific Notes and News 561 



University and Educational News 564 



Discussion and Correspondence: — 



Methods for preparing Animal Material to 



be dissected: Professor R. M. Strong 564 



Scientific Boolcs: — 



McClendon's Physical Chemistry of Vital 

 Phenomena: Professor Ralph S. Lillie. 565 



Proceedings of the National Academy of Sci- 

 ences: Professor Edwin Bidwell WrLSON. 567 



Special Articles: — 



A Selation of Atomic Weights to Atomic 

 Numbers and a Suggested Structure of 

 Atomic Nuclei: Dr. John Q. Stewart. 

 The Aerobic Culture of Anaerobes at Higher 

 Temperatures: Lillian Jordan Ellefson, 

 Ivan C. Hai-l 56S 



The Boston Meeting of the American Chemical 

 Society 571 



IvISS. ictended for publication and books, etc., intended for 

 review sbouJa be sent to The Editor of Science, Garrison-on- 

 Hudson, N. if. 



THE CHEMICAL BASIS OF AXIAL 

 POLARITY IN REGENERA- 

 TION 



When a piece of a stem is cut out from 

 a plant one or more new slioots will usually 

 arise at the apical, and roots at the basal 

 end of the piece. This phenomenon of axial 

 polarity was explained by the older botan- 

 ists as being due to a flow of shoot-forming 

 substances to the apex and of root-forming 

 substances to the base. The gathering of 

 these substances at opposite ends of the 

 piece was believed to be responsible for the 

 phenomenon of polarity in regeneration. 

 While this may or may not be correct, the 

 writer has recently found facts which sug- 

 gest an additional or a diiferent mechanism 

 for this polarity, namely, that the apical 

 bud suppresses the growth of the buds situ- 

 ated more basally in the stem by sending 

 out inhibitory substances in a basal direc- 

 tion. 



The experiments were made on Bryo- 

 phyllum calycinum. Each node of the 

 stem of this plant has two leaves in an oppo- 

 site position, and in the axil of each leaf is 

 found a dormant bud capable of giving rise 

 to a shoot. The line connecting two buds of 

 one node is at right angles to the line con- 

 necting the two buds of the next node. 



Experiment I. — ^A piece of stem, contain- 

 ing six or more nodes, is cut out from a 

 plant, all the leaves are removed and the 

 piece is put into a horizontal position with 

 the line connecting the two buds of the 

 most apical node vertical. In this ease 

 both buds in the apical node may begin to 

 grow, but as a rule only the upper bud will 

 continue to grow, while the growth of the 

 lower bud will soon stop altogether or will 



