578 



NA TUBE 



[February 20, 1908 



jt is, probably, the helium line. Olher evidence and his 

 own observations of the dark D, line in active areas out- 

 side the umbral regions of spots support this view. 



.\ Detailed Stl-dy oi' the Photosphere. — In No. 1895 

 <if N.iTURE (vol. Ixxiii., p. 401, February 22, 1906) we 

 I)ublished an article dealing with Prof. Hansky's study of 

 iho size and movements of the granules comprising the 

 >iilar photospheric surface. Mr. Chevalier, of the 7.6-si 

 Observatory, China, has for some time been engaged on a 

 similar study, and publishes some very interesting results, 

 Avith photographs, in No. i,. vol. xxvii., of the Astro- 

 physical journal (January, p. 12). The principal con- 

 clusions deduced from the results show that on comparing 

 photographs taken at one minute or half-minute intervals 

 the same photospheric granules may be easily recognised, 

 although their shapes and brilliancies undergo considerable 

 ciianges. A more detailed comparison shows changes in 

 their relative positions, the magnitude of the changes 

 differing greatly both in direction and velocity. The veloci- 

 ties obtained range from o to 30 or more kilometres per 

 second, and, in the mean, are much lower than those 

 obtained by Prof. Hansky. 



SECTIONAL ADDRESSES AT THE CHICAGO 

 MEETING OF THE AMERICAN ASSOCIATION. 

 pjV the courtesy of Dr. L. O. Howard, permanent 

 secretary of the American Association for the 

 Advancement of Science, we have been favoured with 

 ■copies of several addresses delivered by chairmen of 

 sections of the association at the recent Chicago meeting, 

 ■of which an account was given in Nature of Januarv 30. 

 Subjoined are summaries of some of the points of interest 

 in these addresses. A summary of the president's address 

 appeared in Nature of January 23. 



Music and Melody. 



In his address to Section B (physics) Prof. \V. C. Sabine 

 chose as his topic " Melody and the Origin of the Musical 

 Scale," the discourse being a critique of views pub- 

 lished fifty-five years ago by Helmholtz in his " Tonemp- 

 findungen." It is pointed out that in part ii. of that 

 work Helmholtz gave a physical and physiological explana- 

 tion of the harmony and discord of simultaneous sounds, 

 and Prof. Sabine briefly • quotes Helmholtz "s description 

 of the structure of the human ear, so far as it is required 

 to explain why overlapping tones produce a sense of dis- 

 cord, thus leading to the necessity of a musical scale with 

 regular intervals for the building up of harmonies. But 

 in applying this principle to account for the origin of 

 such a scale, Helmholtz was met by an apparent 

 anachronism. 



Up to the eleventh or twelfth century only homophonic 

 music existed, this consisting merely in the progression 

 of single-part melody. The existing music of the Oriental 

 and Asiatic races belongs to this type, and Helmholtz, 

 admitting that between sounds which reach the ear in 

 discrete succession there could be neither harmony nor 

 discord, nor beats, sought another explanation for the 

 fact that musical scales were existent long before the 

 introduction of polyphonic and harmonic music. Prof. 

 Sabine now offers a new exnianation of this particular 

 point. AVhen sounds arc produced inside a closed space 

 such as a building, they continue to reverberate for a 

 certain interval after the exciting source has ceased to 

 exist. In this connection Prof. Sabine gives (without, 

 however, specifying the units) a list of the absorbing 

 powers of different substances. It follows that as soon as 

 melodies were performed inside buildings such as temples 

 of worship, the consecutive notes became blended, and this 

 overlapping produced all the conditions necessary for the 

 production of the harmonics and discords discussed by 

 Helmholtz in explanation of the chorda! use of the musical 

 scale. This proposed theory of Prof. Sabine's would (so 

 It is claimed) account for the absence of a musical scale 

 among the native tribes of Africa. 



The Problem of Heredity. 



It is a sign of the times that the addresses delivered 

 tefore the American .Association by Dr. D. T. Macdougal, 



NO. TQ9Q, VOL. 77] 



a botanist, and by Dr. E. G. Conklin, a zoologist, uw 

 not about botany and zoology respectively, but that both 

 deal with heredity ; and it is evidence of the vastness of 

 the topic with which they deal that, though they botli 

 tieat of the mechanism of heredity, their two addresses 

 do not overlap. Both addresses are admirable examples 

 of what such addresses should be. Their opening sentences 

 exhibit a breadth of view which, if we may say so, has 

 not been a distinguishing feature of a great deal of recent 

 .■\meric-.ui biological literature ; and both addresses contain 

 such a wealth of references to, and accounts of, new 

 observations and experiments which bear on the interpreta- 

 tion of fundamental problems that the earnest biologist 

 will do well to read them both. 



Dr. Macdougal opens his address on " Heredity and 

 Knvironic Forces " with some well-needed remarks on the 

 assumption that the changes which ensue when a plant 

 is transported to a violently different environment — as, for 

 example, when a mesophyte is grown as a xerophyte — are 

 adaptive changes. According to Dr. MacDougal, these 

 are not only assumptions, but unwarrantable ones. 

 Certain of the changes which accompany the transporta- 

 tion do undoubtedly benefit the plant in its new surround- 

 ings, " but results of the opposite character are 

 encountered. Thus in my experiments with Roripa, the 

 .■\merican w^atercress, it was seen to bear filiform, dissected 

 leaves when submerged, linear dissected leaves when 

 emerscd, but when acclimatised at the Desert Laboratory 

 developed broadly ovate, almost entire lamirtEe." Similarly 

 etiolation, usually regarded as an adaptive change which 

 enables the plant to lift its head above objects which keep 

 the light from it, was found to occur in less than half 

 the species tested, the majority " showing thickened organs 

 and other useless alterations." Lastly, he cites the proof 

 given by Lloyd that the movements of stomata are not 

 adaptive or regulatory with respect to transpiration. We 

 can heartily endorse Dr. Macdougal 's conclusion on this 

 part of his subject (as he happily phrases it in his native 

 tongue), "that the entire matter of causal adaptations 

 is in need of a basal re-investigation from an entirely new 

 view-point." 



But the most interesting part of this address is that 

 which deals with the author's successful attempts to 

 modify permanently the germ-plasms of plants by subject- 

 ing them to the influence of various chemicals. " It was 

 found that the injection of various solutions into ovarier. 

 of Raimannia was followed by the production of seeds 

 bearing qualities not exhibited by the parent, wholly 

 irreversible, and fully transmissible in successive genera- 

 tions. One of the seeds produced by a plant of Oenothera 

 biennis which had been treated with zinc sulphate differed 

 so w'idely from the parental form that it could be dis- 

 tinguished from it by a novice. This new form " has 

 been tested to the third generation, transmits all its 

 characteristics fully, and does not readily hybridise with 

 the parent even w-hen grown so closely in contact with it 

 that the branches interlock." Results as remarkable as 

 this need confirmation, and it is to be hoped that similar 

 experiments will shortly be undertaken in this country. 



In his address on "The Mechanism of Heredity," Dr. 

 E. G. Conklin suggests an answer to the question which 

 alwavs puzzles the philosophical biologist, " What exactly 

 is the problem of heredity? How does it differ from that 

 of development? " Dr. Conklin 's answer is what at firs- 

 sight would seem to be the natural and logical conse- 

 quence of the acceptance of Weismann's doctrine of the 

 continuity of the germ-plasm ; it is, in fact, that there is 

 little difference between the tw'O problems. " Indeed. 

 Heredity is not a peculiar or unique principle ; for it is 

 onlv sirnilarity of growth and differentiation in successive 

 generations. ... In fact, the whole process of develop- 

 ment is one of growth and differentiation, and similarity 

 of these in parents and offspring constitutes hereditary 

 likeness. The causes of heredity are thus reduced to th.^ 

 causes of the successive differentiations of development, 

 and the mechanism of heredity is merely the mechanism 

 of differentiation." Having reduced the problem of 

 hereditv to this. Dr. Conklin goes on to consider the 

 evidence for the view that the chromosomes are solely 

 concerned in the process of differentiation, and expresses 

 himself as definitely opposed to that view. He is not 



