SCIENCE 



Friday, April 23, 1915 



CONTENTS 



Badio-activity and the Periodic System: Dr. 

 Francis P. Venable 589 



Some Fallacies in the Arguments against Full- 

 time Clinical Instruction: Db. Major G. 

 Sbblig 594 



Charles E. Bessey: Professor John M. 

 Coulter 599 



Franlc Olin Marvin: Professor E. H. S. 

 Bailey 600 



The Chemical Industry in Great Britain .... 601 



Interstate Conference on Cereal Investigations. 602 



The Harpswell Laboratory 603 



Scientific Notes and News 604 



University and Educational News 607 



IHscussion and Correspondence: — 



The Fundamental Equation of Dynamics: 

 Professor L. M. Hoskins. The Nature 

 of the Ultimate Magnetic Particle: K. T. 

 COMPTON, E. A. Trousdale. The New 

 Glacier Park: Professor Albert Perry 

 Brigham 608 



Scientific BooTcs: — 



Ball on the Molluscan Fauna of the Orthau- 

 lax Pugnaa Zone of the Oligocene of Tampa, 

 Florida: Professor G. D. Harris. Sam- 

 marsten's Text-hooTc of Physiological Chem- 

 istry: Professor Otto Folin 612 



Notes on Entomology : De. Nathan Banks . . 614 



Special Articles: — 



The Assumption of Male Secondary Sex 

 Characters iy a Cow: Dr. Raymond Pearl 

 AND Dr. Frank M. Surface. The Feeding 

 Power of Plants: E. Teuog 6l5 



The Society of American Bacteriologists : Dr. 

 A. Parker Hitchens 618 



MSS. intended for publication and books, etc., intended for 

 reriew should be sent to Frofessor J. McKeen Cattell, Garrison- 

 On-HudsoD. N. Y. 



BABIO-ACTiriTY AND THE PEBIODIC 



SYSTEM-!- 



The periodic system of the elements has 

 for nearly half a century proved a most 

 puzzling and absorbing problem to chem- 

 ists. It has been called a law, but while 

 there is undoubtedly an underlying law or 

 laws, I doubt whether we have as yet any 

 very clear conception of them. Certainly, 

 the usual statement that the properties of 

 the elements are periodic functions of their 

 atomic weights was never strictly true, 

 even in days of partial knowledge, and is 

 much less true now. It was neither the 

 periodicity "of the geometers," as Men- 

 deleef himself said, nor the function of the 

 mathematician. Indeed, we have now come 

 to a view where, apparently, we must 

 abandon the atomic weight as the only or 

 even the chief determining variable. 



The truth is that for many years after 

 its announcement it was more truly a work- 

 ing hypothesis, and a great deal of work 

 had to be and still has to be done before it 

 can attain to its completed form. It con- 

 tains much that is true, has been most use- 

 ful as a guiding principle, and has shown 

 a wonderful power of adjustment to new 

 facts and increasing knowledge. 



It was in 1895 that the system had to 

 adjust itself to the first severe jolt which 

 it received through the discovery of argon 

 and helium, and three years later, of other 

 inactive, monatomic elements. The neces- 

 sity for readjustment here had been in part 

 foreseen. The abrupt change in the pro- 

 gression of the elements from strongly elec- 

 tro-negative fluorine to strongly electro- 



1 Bead before the Elisha Mitchell Scientific So- 

 ciety, March 9, 1915. 



