56 



NATURE 



{May 17, 1888 



for very feeble magnetizing forces, iron may be diamagnetic 

 That suggestion was confessedly speculative ; its basis was the 

 notion that the Weber- Ampere electro-magnetic molecules suffer 

 something akin to static friction when the process of magnetiza- 

 tion attempts to bring them into alignment. Since it was thrown 

 out, Lord Rayleigh has proved that the susceptibility of iron is 

 constant, and has a fairly high positive value, for magnetic forces 

 ranging from 003 to 004 C.G. S. downwards. Below the 

 lowest force he has investigated, it is still conceivable that there 

 may be a change in the susceptibility, but it is extremely im- 

 probable. In all likelihood, Lord Rayleigh's straight line in 

 the curve of B and H or of I and H extends back to the origin. 

 This at least is certain, that if there is any region at the begin- 

 ning of magnetization within which the permeability is less than 

 unity, or even no more than unity, it must be so infinitesimally 

 narrow that its existence has no practical interest. For such 

 magnetic forces as act on a lightning-conductor when a dis- 

 charge is passing, iron is, beyond any question, strongly paramag- 

 netic, and the self-induction with the iron conductor consequently 

 greater than with the copper. J. A. EwiNG. 



Dundee, May n. 



Notes on the Reproduction of Rudimentary Toes in 

 Greyhounds. 



At the present writing, I have under my observation a fine 

 male, light clay-coloured, smooth haired greyhound, which at 

 certain intervals well illustrates the reproduction of the rudiment- 

 ary digits of its feet, after they haVe been accidentally amputated. 

 To-day this dog has growing on the inner aspects of both its 

 fore and hind feet, and situated some 9 centimetres above the 

 soles, on each limb, a strong rudimentary toe. If we choose, 

 say, this toe on the right hind foot as an example of them all, we 

 find it to be loosely attached, rather more than a centimetre 

 long to the base .of the claw, which latter is large and strong, 

 powerfully curved, and fully as big as any of the claws on the 

 foot phalanges, I further find that this toe has a well-marked pad 

 on its under side, but careful examination fails to detect any 

 bone in the proximal joint, from which I also infer that the 

 ungual phalanx likewise lacks one, though this is not so easily 

 determined without cutting through the horny theca forming the 

 claw. About four months ago this dog was coursing hares over the 

 prairie of this region, which chances to be overgrown with a 

 stiff growth of sage-brush, about 2 feet to 3 feet high. The wiry 

 stems of this plant, as the dog bounded among them, snipped off 

 all four of these rudimentary digits, close down to the leg in each 

 case, as nicely as though it had been done with a knife, leaving 

 linear wounds about half a centimetre long. Now, instead of 

 the lips of these wounds healing across, as one would naturally 

 suppose they would, they immediately form the basis, in each 

 case, for the growth of another rudimentary clawed toe, fully as 

 perfect as the one which originally sprang from the same site. 

 These subsequent growths take about three months to attain 

 their full size again, when they are very likely to be removed by 

 a similar process, and once more grow out as before, and so on 

 indefinitely. 



From several points of view, this case, as occurring in a 

 vertebrate so high in the scale as a dog, has interested me 

 very much indeed, and I further find that it is no uncommon thing 

 to meet with greyhounds that have never possessed these rudi- 

 mentary pollices and halluces, and it is fair to presume that in 

 this race they are gradually disappearing. 



R. W. Shufeldt. 



Fort Wingate, New Mexico, March 28. 



Dreams. 



In discussing the differences between dreams and real life, 

 Schopenhauer expresses the opinion that the distinction between 

 these two activities of our representative power consists merely 

 in the possibility of the representations of real life being con- 

 nected in an uninterrupted successive series, while dreams 

 resemble the separate pages of a book torn asunder, and put 

 together again in complete confusion. Some personal observa- 

 tions of my own do not quite agree with this view. I have 

 watched my dreams for some years, and have remarked that 

 many of them are connected with one another in separate series. 

 It happens to me very often that my dreams consist of a series 

 of representations logically developed (although sometimes the 

 logic is absurd) from other series of representations dreamed long 



before. It would be interesting to know if anyone else has 

 observed anything of this kind. A. Bialoveski. 



Oostkamenogorsk, Western Siberia, April 6. 



"Antagonism." 



Mr. Collins (Nature, May 3, p. 7) claims that Mr. 

 Herbert Spencer anticipated Sir Wm. Grove and Prof. Huxley 

 in the expression of the idea of antagonism. I think that 

 priority to all of them must be given to the author of Eccle- 

 siasticus in the Apocrypha, who says (chap, xlii., verse 24), 

 "All things are double, one against the other. He hath made 

 nothing imperfect." Thomas Woods. 



Parsonstown, May 13. 



SUGGESTIONS ON THE CLASSIFICATION OF 

 THE VARIOUS SPECIES OF HEAVENLY 

 BODIES. 1 



V. 



Classification into Species. 



V\7"E are now in a position to apply all that has gone 

 ** before in a summarized statement of the various 

 spectral changes, including those connected with hydrogen, 

 which take place not only in these objects studied by 

 Duner, but in those others to which I have referred as 

 forming the true beginning of the group. 



The following statement, however, must not be taken 

 as anything else than a first approximation to the real 

 criteria of specific differences. I am convinced that 

 further thought is required on it, and that such further 

 thought will be well repaid. 



The Sequence of the Various Bands in the Spectra of the 

 Elements indicated by Bodies of the Group. 



In comparing the spectrum of an element which has 

 been mapped in the laboratory with the absorption bands 

 in the spectrum of a " star," we need only consider those 

 bands and flutings which stand out prominently and are 

 the first to flash out when there is only a small quantity 

 present. Thus, in the flame spectrum of barium there is 

 an almost continuous background of flutings with a few 

 brighter bands in the green, and it is only important to 

 consider the bands, as the flutings would mainly produce 

 a general dimming of the continuous spectrum. In 

 order to show at a glance what portions of the spectrum 

 of an element it is most important for us to consider in 

 this discussion, I have reconstructed the map of low- 

 temperature spectra which I gave in my previous paper, 

 with reference to those elements which are indicated 

 in the spectra of bodies of Group II. Five orders of 

 intensities are represented, the longest lines, flutings, or 

 bands being the brightest. The lines, flutings, or bands 

 in the lowest horizon, in the case of each element, are 

 those which are seen at the lowest temperature, and which 

 are the first to appear when only a small quantity of 

 substance is present. Those in the upper horizons are 

 the faintest, and are only seen when the temperature is 

 increased, or a considerable amount of the substance is 

 volatilized. The map shows that if there are any indica- 

 tions of magnesium, for instance, in bodies of low tem- 

 peratures, the fluting at 500 will be seen, possibly with- 

 out the other flutings or lines. The first indications of 

 manganese will be the fluting at 558, and so on. Again, 

 on account of the masking effect of the spectrum of one 

 element upon that of another, we may sometimes have an 

 element indicated in a star spectrum, not by the brightest 

 band or fluting in its spectrum, but by the second or even 

 third in brightness ; this, of course, only occurs when the 

 darkest band falls on one of the brightest flutings of 



1 The Bakerian Lecture, delivered at the Royal Society on April 12, by 

 J. Norman Lockyer, F.R.S. Continued from p. 35. 



