572 



SCIENCE 



[N. S. Vol. LI. No. 1327 



tion of an iodine molecule may consist in its 

 dissociation and the ionization of one of the 

 parts by the same electron impact. 



This kind of a process has been suggested to 

 estimate the beat of dissociation of hydrogen 

 from ionization data, but the present work is 

 the first, as far as we are aware, to give direct 

 evidence as to which ionization effect is due 

 to the atom and which to the molecule. It is 

 probable that this method may be of value in 

 determining heats of dissociation v^hich are 

 too high to be found by ordinary methods. 



K. T. COMPTON, 



H. D. Smyth 

 Princeton Universitt, 

 May 18, 1920 



THE AMERICAN PHILOSOPHICAL 

 SOCIETY 



At the 1920 general meeting of the American 

 Philosophical Society, held on April 22, 23 and 

 24, in Philadelphia, the following comprehensive 

 program was followed. 



April SS, S o'clock 



William B. Scott, D.Sc, LL.D., president, in the 



chair 



Beach protection worls: Lewis M. Haupt, Phil- 

 adelphia. 



Geographic aspects of the Adriatic problem: 

 Douglas W. Johnson, professor of physiography 

 at Columbia University. (Introduced by Professor 

 W. M. Davis.) 



The reefs of Tutuila, Samoa, in their relation to 

 coral reef theories: Alfred G. Mayor, director of 

 the department of marine biology, Carnegie Insti- 

 tution of Washington. 



A distribution of land and water on the earth: 

 Harry Fielding Eeid, C.E., Ph.D., professor of 

 dynamic geology and geography, Johns Hopkins 

 University. The conception of the land of the 

 earth as being a deeply dissected and loosely 

 joined together mass, with its center about half 

 way between the equator and the poles, explains 

 nearly all the characteristics of the distribution of 

 land and water, such as: the antipodal relation, the 

 concentration of land about the north pole and of 

 water about the south pole, etc. 



Thyroxin: E. C. Kendall, Ph.D., of the Mayo 

 Clinic, assistant professor of chemistry of the 

 University of Minnesota. (Introduced by Dr. 

 Philip B. Hawk.) 



The dualistic conception of the processes of life : 

 Samuel J. Meltzer, M.D., LL.D., head of depart- 

 ment of physiology, Rockefeller Institute for Med- 

 ical Research, New York. Animal life manifests 

 itself by an uninterrupted stream of various forms 

 of activities. But each of the activities is discon- 

 tinuous, it is interrupted by a longer or shorter 

 resting phase. Most physiologists look at life proc- 

 esses from a monistic point of view. In their 

 opinion only action needs a cause; the reduction in 

 action or the resting phase needs no special inter- 

 pretation; they are simply due to a reduction in 

 the eitent of the cause or to its entire absence. 

 However, seventy-five years ago, it was discovered 

 by the brothers Weber that stimulation of the 

 peripheral end of a vagus nerve stops the beating 

 of the heart which remains resting in an increased 

 state of diastole. Here a special cause, a stimu- 

 lation of a nerve going to a muscle, causes a rest- 

 ing phase in the heart muscle. This action was 

 termed inhibition. In the three quarters of a cen- 

 tury since this discovery was made, numerous in- 

 stances of inhibition in the various processes of 

 animal life were discovered. From all the facts as 

 they are known now, it must be assumed that there 

 is in the aninial life probably not a single function 

 in which the phenomenon of inhibition is mot an 

 important factor. The part played by inhibition 

 is on one hand to remove obstacles to an efficient 

 action, and on the other hand to permit the living 

 tissues to perform in the resting phase anabolic 

 processes, that is, to build up the tissues or to re- 

 plenish the material expended during the action 

 phase. The dualistic conception of the life proc- 

 esses may be presented as follows. Irritability is 

 a characteristic property of all living tissues. 

 Irritability means the property of the tissues to 

 react with a change in each state to a proper stim- 

 ulus. The change may consist in an excitation, an 

 increase of activity, or an inhibition, a decrease 

 in activity. Each and every state of life of the 

 plain tissues or of the complex functions is a re- 

 sultant from the combination of the two antagon- 

 istic factors, excitation and inhibition. In a state 

 of utmost rest the factor of inhibition prevails 

 greatly; but there is still a remnant of the factor 

 of the excitation which permits the tissues or the 

 functions to remain in a state of tonus, of dor- 

 mant life. On the other hand, in a state of ex- 

 treme excitation there is stUl a remnant of the 

 factor of inhibition which prevents the excitation 

 from completely destroying the life of the involved 

 tissues. 



