December 28, 1905J 



NA TU RE 



197 



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 port of Nature. 

 .V,> notice is taken of anonymous communications.] 



Magnetic Storms and Aurorae. 



The observations of your correspondents Mr. Rowland 

 A. Earp and Mr. R. Langton Cole, published in Nature 

 of November 23 (pp. 79-80), remind me that an aurora was 

 also visible here (Cape Breton Island, Nova Scotia) on 

 November 15 about 6 p.m., Halifax time. 



Although "only faintly visible on account of the twilight 

 and the condition of the sky, the aurora was evidentlj "I 

 considerable intensity, throwing up streamers to the zenith. 



I looked out again at 7 p.m., but could detect no signs 

 of auroral activity then. Occasional watch was kept upon 

 the northern sky' during the rest of the night in hopes of 

 1 recurrence, but nothing further was seen. 



Alexander Graham Bell. 



Beinn Bhreagh, near Baddeck, Nova Scotia, 

 December 9. 



With reference to a letter from Dr. Chree in Nature 

 of November 30 (p. 101) upon the magnetic storm of 

 November 15, it may perhaps be of interest to mention 

 that, according to a notice in the newspaper Finmarken, 

 the aurora of that day in Yardo (lat. 70 22') was by 

 far the most splendid seen there for many years. It is 

 described as bright red all over, and, when most vivid, 

 forming a belt over the whole sky from south-west to 

 north-east. At last, about 11 p.m., the light gathered in 

 the southern sky, making the impression of a huge fire 

 some forty kilometres away. 



Here in Christiania the sky was overcast, except a low- 

 horizontal stripe in the north-west, where the vivid 

 greenish light was moving to and fro about 7 p.m. 



H. Gedmuyden. 



University Observatory, Christiania, December 16. 



The Origin of Variations in Animals and Plants 



Having found much ambiguity in discussions of this 

 subject, I have tried to formulate briefly the probable facts, 

 as they appear to me. 



(1) In the beginning, the germ-plasm was not separated 

 from the somato-plasm, and hence it is assumed that 

 " acquired characters " were inherited, and, we must sup- 

 pose, still are by the protozoa. It seems probable, how- 

 ever, that the obvious effects of the environment were not 

 permanent, but were recovered from in a few generations 

 of cells or individuals, much as they are frequently re- 

 covered from in the metazoa during the life of a single 

 individual. When they were too severe, they probably 

 resulted in the death of the affected individuals or strains. 

 In other words, there has been no regular " inheritance 

 of acquired characters " among the protozoa any more 

 than among the metazoa. 



On the other hand, it seems reasonable to suppose that 

 there were other more subtle effects, which in various slight 

 ways changed the molecular arrangements or composition 

 of the plasm, and effects so produced would be permanent 

 until further changes of a similar nature took place. 



The extraordinary permanence of type of protozoan and 

 protophytan species, both in time and space, compels us 

 to discard the idea that they are easily modified by external 

 or any other conditions ; while their marvellous diversity 

 shows that thev are capable of extraordinary modification. 

 What causes the molecular changes (presumably nobody 

 denies that they take place) is not apparent to us, partly 

 because the phenomena must be very difficult (or 

 impossible?) to demonstrate, and partly, perhaps, because 

 they have been overlooked, all attention having been given 

 to the obvious but less significant changes. Recent physical 

 science has made us familiar with all sorts of subtle in- 

 fluences, and we do not know how any of them might 

 affect the complex molecule of a living creature. Sub- 

 stances which hitherto behaved in a perfectly well 



NO. 1887, VOL 73] 



known manner have given us surprises when we placed 

 them in the presence of something new. So it may well 

 be with the living molecule, and what we call " great 

 changes in environment " may be nothing at all to it, com- 

 pared with subtle influences which entirely escape our 

 observation. 



(2) In the first place, the molecular changes may have 

 been good, bad, or indifferent (as tested by the prosperity 

 of the creatures) ; but very soon selection would get in 

 its work, and those types' of plasm which responded in 

 certain ways to the more usual influences would be per- 

 petuated. ' Hence it would presently be found that 

 variations were no longer indefinite, but were in certain 

 prevalent directions — as they assuredly are. 



(3) The fact that protoplasm shows such very definite 

 tendencies low down in the scale of life (so that the 

 hydrozoa, for example, seem wonderfully prophetic of sub- 

 sequent evolution) might be used as an argument that life 

 did not originate upon this earth, but came here with a 

 long history already behind it. 



(4) In the metazoa the matter is immensely complicated, 

 because we have in each individual not one, but a larg" 

 number of more or less independent variables. Neverthe- 

 less, I cannot doubt that the germinal elements are, as I 

 have supposed in the protozoa, caused to vary (and nobody 

 disputes the variation) by external influences ; yet, from 

 the selection and evolution of ages, their reactions have 

 become so definite that we cannot see in them anything 

 but " the nature of the beast." 



1 SI Since those germs would be selected (through their 

 somata) which reacted in such a way as to produce the 

 most favourable variations, it becomes easy to see why 

 certain kinds of variation may be carried beyond the point 

 of maximum utility. They are like habits, which may be 

 formed in response' to certain needs, but which afterwards 

 become tyrannical, because the individual has acquired the 

 property "of responding to particular stimuli, and cannot 

 stop when the stimuli become more numerous, or the effects 

 accumulate unpleasantly. 



(6) The fact that certain genera (e.g. Rubus, Aster, 

 Agriolimax) are extremely prolific in species in some 

 regions, and very little so in others, seems to show that 

 some external influences have been at work in the former 

 case and not in the latter. We may also direct attention 

 to the effects of changed conditions in producing variability 

 (e.g. in Helix nemoralis), and to the evolution of similar 

 types in different regions. 



(7) It may well be that the appearance of characters in 

 the soma does not always or often follow in the generation 

 after the germ is affected (cf. Nature, February 16, p. 366). 



T. D. A. CoCKERELL. 



Boulder, Colorado, U.S.A., December 1. 



An Acoustical Method for the Demonstration of the 

 Magnetism of Liquids. 



One end of a glass tube, about 5 mm. internal diameter 

 and 1 mm. thick, is heated in a blowpipe flame until the 

 molten end contracts to a round nozzle, leaving a small 

 aperture of less than half a millimetre at the middle. 

 The other end of this tube is connected by a caoutchouc 

 tubing to an air-bag of considerable capacity, which _ is 

 pressed by a constant weight. The nozzle is wet with 

 a drop of liquid. By opening the cock of the air-bag, the 

 air escapes through the nozzle and produces a clear musical 

 sound, the pitch of which depends upon the dimensions of 

 the nozzle as well as the quantity and the nature of the 

 liquid ; it varies also with the pressure of the air inside 

 and the inclination of the tube to the vertical. 



If the nozzle, wet with a magnetic liquid, be brought 

 close to the conical pole-piece of a strong Faraday's electro- 

 magnet and the field excited, the pitch of the sound changes 

 more or less according as the magnetic susceptibility of 

 the liquid and the gradient of the field is greater or less. 

 With concentrated solution of ferric chloride or manganese 

 chloride, a change amounting to an interval of a third is 

 easily obtained. 



The details have been published in the Proceedings of 

 the Tokio Physico-mathematical Society, vol. ii., No. 26. 



T. Terada. 



Science College, Imperial University, Tokio, November 5. 



