4O0 



NATURE 



[July 13, 1916 



of causes which determine the resemblance 

 between individuals genetically related. "The 

 critical problem of inheritance is the problem of 

 the cause, the material basis, and the maintenance 

 of the somatogenic specificity of germinal sub- 

 stance." Towards a solution of this problem con- 

 tributions have been made along four lines — bio- 

 metric, Mendelian, cytological, and embryological, 

 and each of these methods is valuable and neces- 

 sary. But they have at least one fundamental 

 limitation in common. "This is that they offer 

 ho means of directly getting at any definite in- 

 formation regarding the origin, cause, or real 

 nature of that specificity of living material which 

 is the very foundation of the phenomenon of 

 heredity." The most hopeful line of attack on 

 this outstanding problem is biochemical. 



A second chapter deals with the value and like- 

 wise the limitations of biometric methods, and it 

 is full of good sense and good counsel. " To 

 attempt to draw conclusions in regard to inheri- 

 tance from studies involving the correlation 

 method alone is futile." Third comes a useful 

 essay on the nature of statistical knowledge, 

 which is not, as some would have us believe, a 

 higher kind of knowledge than that obtained in 

 other ways. The statistical method furnishes 

 shorthand descriptions of groups and a test of the 

 probable trustworthiness of conclusions. 



" It is, however, a descriptive method only, and 

 has the limitations as a weapon of research which 

 that fact implies." After a more technical chapter 

 on certain logical and mathematical aspects of the 

 problem of inbreeding, the author completes his 

 interesting volume with the warning that the value 

 of research in genetics is to be judged by its con- 

 tributions to knowledge rather than by its aid to 

 the practical breeder — useful as that aid may be. 



The Universal Mind and the Great War. Out- 

 lines of a New Religion, Universalism, based on 

 science and the facts of creative evolution. By 

 E. Drake. Pp. vii + loo. (London : C. W. 

 Daniel, Ltd., n.d.) Price 2S. 6d. net. 

 There is much honest and suggestive thinking 

 in this book, though the writer is sometimes both 

 pedantic and ill-informed. Having proclaimed 

 the bankruptcy of all dogmatic religion, all philo- 

 sophy, and all ethics, he proceeds to give us the 

 right thing. Matter and mind are the two cer- 

 tainties ; they are entities, of which we can know 

 only the manifestations. The universal mind is 

 individualised in each living organism, the crea- 

 tive intellect directing matter from within. God 

 is in us ; we are His direct personification. From 

 the first beginnings of life on the planet He has 

 been moulding matter for His ends of manifesta- 

 tion, dropping the saurian forms, e.g., when not 

 found to work, and trying another tack. He is 

 continually fighting matter, aiming at fuller con- 

 trol, fuller manifestation ; and matter is so big and 

 strong that only a bit at a time can be grappled 

 with — i.e., the part which thereby we see as 

 "alive." At death the mind that was in the 

 organism survives, but in what form — individual- 



NO. 2437, VOL. 97] 



ised or not — we cannot know. The whole argu- 

 ment is in the right direction, though it is crudely 

 put; if the author had read Fechner and Samuel 

 Butler he might have improved it. Both of these 

 see God as Logos manifesting through matter ; 

 but Fechner from the beginning, and Butler after 

 trying a theory almost exactly identical with Mr. 

 Drake's and finding it unsatisfactory, accept Him 

 as energising not only through that small portion 

 of matter which we call "hving," but through all 

 the matter of the universe. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Gravitation and Temperature. 



I SHOULD like to make a statement on the very 

 suggestive contribution by "J. L." in Nature, June 15, 

 regarding my result of a temperature effect for 

 gravitation of +1-2x10-* per i°C. The confirmation, 

 or otherwise, of this result will come, of course, from 

 the laboratory, not the study. Still, a discussion at 

 this difficult juncture might define the issue and per- 

 haps indicate the best line for further experiment. 



To take the scanty known data chronologically : 



I. From Kepler's third law we deduce that gravi- 

 tational mass (g.m.) and inertia mass (i.m.) vary 

 together at the same rate, if at all, with tempera- 

 ture change. The mean temperature of the larger 

 planets is probably much higher than that of the 

 smaller ones. Thus if it were established that at 

 these high temperatures g.m. rises with temperature, 

 i.m. must rise proportionally. Any small departure 

 from this principle would apj>ear as a change in the 

 mean motion for the observed distance, not as a 

 periodic inequality ; so it would be cumulative, and, 

 with the great accuracy of modern astronomical 

 methods, should be observed, unless very small. No 

 such effect is known. 



II. The pendulum experiments of Bessel establish 

 the same principle, but since the temperature range 

 is very small, this test is probably much less severe. 



III. Poynting . and Phillips found that for change 

 in temperature of 100° in a mass of 200 grams, 

 counterpoised on a balance, the change in g.m. is 

 less than i/io* per 1° C. This very exact and direct 

 result, taken in conjunction with I. and II., would 

 seem to show that in the case of a gravitational 

 couplet of a very large mass M and a small mass m 

 the temperature of the latter can vary considerably 

 at ordinary temperature without sensible change in 

 g.m. or i.m. 



IV. My result, quoted above, shows that when M, 

 but not m, is raised in temperature, there is an in- 

 crease in g.m. It will be seen that this case differs 

 from I., II., and III., in that here the large, not the 

 small, mass has temperature varied. My result 

 appears to be in direct conflict with III. Can we 

 make any justifiable physical assumptions whereby 

 this seeming conflict may disappear? 



A simple view of the effect of temperature on 

 attraction is that the gravitational masses M, m 

 increase with temperature, and the two increased 

 masses, M(i + aT) and m(i + at), would be multiplied 

 together to obtain the resulting attraction Thus, 



