278 



SCIENCE. 



discrimination : " moreover the entire brain of an insect 

 is white, as are all the ganglia." 



On page 226, he says that the outer part of the brain 

 is made up of a "slightly darker, usually pale grayish, 

 white portion " — , where the tissue consists of small gan- 

 glion cells, it is naturally .... rather darker than 

 in those regions where the tissue consists of the more 

 loosely disposed, large ganglion cells." 



So that we have a fundamental contradiction in refer- 

 ence to an alleged fundamental distinction, quite aside 

 from the notorious fact that in the lowest vertebrates the 

 nervous system is as " white" as in insects, and that the 

 convoluted " mushroom " body or " cerebrum " of the 

 ant contains sharply demarcated gray and white sub- 

 stances. 



The chapter is accompanied, as stated, by plates of 

 great value, most of these being fac similes of sections 

 prepared by Mr. Norman J. Mason. On the whole, 

 nothing new is added to our knowledge of the adult in- 

 sectean brain in general, or the locust's in particular, that 

 has not been carefully reported by Floegel, Newton and 

 Michels. But through the great patience and skill of Mr. 

 Mason, Professor Packard has been enabled to study sec- 

 tions from the embryo brain, a subject not yet worked up, 

 owing to the difficul'v of preparing the specimens. The 

 most important results obtained is that the nerve-fibres 

 develop from an originally finely granular substance, 

 thus confirming the observations of Schmidt and Hensen 

 for the mammalian embryo. 



In view of the loudly trumpeted theory recently revived 

 by Dr. J. J. Mason, after having repeatedly received the 

 coup de grace at the hands of Stieda, Meynert and others, 

 that large cells are motor, it is interesting to note that 

 those of the optic ganglion in the locust are among the 

 largest cells in its nervous system. R. C. S. 



CORRESPONDENCE. 



The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous communi- 

 cations.] 



To the Editor of " Science." 



Limax maximas L. A specimen of this slug was 

 brought me May 16. It came through a faucet con- 

 nected with the water works. Being an introduced 

 species and not frequently found, this fact may be of 

 interest. 



Polygala pancifolia, wild. Specimens with pure white 

 flowers have been sent from Lunenburg, Mass., two 

 years in succession. J. H. PlLLSBURY. 



Springfield, May 27, 1881. 



SPECTRUM ANALYSIS. 



At a meeting of the Royal Astronomical Society held 

 on the 13th of May, Mr. Norman Lockyer asked permis- 

 sion to offer the following!' address. He said : 



" The chemical constitution of the heavenly bodies is 

 one that demands some attention from astronomers. 

 Twenty years ago the observations of Kirchoff and Stokes 

 enabled us to get some glimpses into the chemical con- 

 stitution of the sun. Kirchoff's view was that substances 

 with which we are acquainted exist in the atmosphere of 

 the sun, and that their presence was demonstrated by an 

 exact matching both with respect to wave-length and in- 

 tensity of the lines of certain chemical elements. Before 

 his time Frauenhofer had noted the coincidence of the 

 bright yellow line of sodium with the D line in the solar 

 spectrum, but Kirchoff showed that also in the case of 

 iron, magnesium, cobalt and several other substances 

 there were coincidences between lines, which went to 

 show that what was true with respect to sodium was true 

 vith respect to these other bodies. Nine years ago, we had 

 not merely the opportunity of comparing these bright 

 lines in the spectrum of the sun's atmosphere, as revealed 



to Frauenhofer, but we had the opportunity of studying 

 the spectra obtained from very small portions of the sun's 

 atmosphere, in regions where we should expect an exceed- 

 ingly high temperature —namely, in the regions of spots 

 and in the regions of prominences. When we began to 

 examine these spectra, we found that the lines were 

 thickened, and the ques'ion appeared much less clear 

 than it did before. 01460 iron lines recorded by Kirchoff, 

 only three were observed in the prominences, and these 

 were not the lines that were seen thickened in spots ; so 

 that a great many fresh questions were raised, and the 

 idea of the decomposition of the iron by the high tem- 

 perature was forced upon us. I wish to bring before you 

 to night the results of some purely astronomical inquiries, 

 lately undertaken by the Solar Physics Committee with 

 respect to the behavior of the lines in the spectra of spots 

 and prominences. We had before us the admirable work 

 undertaken by Prof. Young in 1872, on the spectra of the 

 prominences ; but his observations only lasted for a 

 month, and we felt that we wanted more facts, so what 

 we have been doing at Kensington during the last two 

 and a half years, has been to obtain and tabulate the 

 spectra of a hundred sunspots, and these we have com- 

 pared with the Italian observations of prominence 

 lines. It was impossible to note and map down 

 the behavior of all the lines in the spot spectra. 

 The Committee, therefore, attempted something which 

 was more modest, and contented themselves with ob- 

 serving twelve lines in the most easily visible part 

 of the spectrum, between F and D (pinned to the black- 

 board was a diagram with the spectra observed placed 

 one beneath the other, at the top were the iron lines of 

 the Frauenhofer spectrum stated by Angstrom to be co- 

 incident with the bright lines of iron). The first point 

 which strikes one on examining this diagram is the enor- 

 mous number of iron lines, both in the solar spectrum 

 and in the iron spectrum, as mapped by Angstrom, who 

 used an electric arc of thirty or more Bunsen cells. They 

 remind one of a great piano, only a few notes of which 

 are played over and over again in the spot spectra, but 

 always producing a different tune. If you examine the 

 lines individually, you will find that every line has been 

 seen with every other line. One is struck by the mar- 

 vellous individuality, so to speak, of each. The lines do 

 not go in battalions, or companies, or corporal's files, but 

 in single units. The great importance of obtaining these 

 observations is not so much for the observations them- 

 selves, as for the comparison they enable us to make 

 with the observations of the lines in prominences, be- 

 cause the prominences are hotter than the spots. The 

 spots are caused by down-currents where the solar at- 

 mosphere is brought down from cooler regions. They 

 are opposed to prominences, which are ejections of 

 heated matter from the interior of the sun. Here (point- 

 ing to the diagram) we have arranged the observations 

 of prominences by Tacchini since 1872. What is-the 

 result ? First of all, you will note a vety great simplifi- 

 cation ; the brightest part of the sun has given the fewest 

 lines. Next, there is not a single line common to the 

 two series. In passing from the iron lines in the spots to 

 the iron lines in the flames we pass from one spectrum to 

 another, and the two spectra are as distinct from one an- 

 other as the spectrum of magnesium is distinct from the 

 spectrum of chlorine, or any other substance you please. 

 These phenomena are the last we should expect. We 

 can understand that a difference in the quantity of iron 

 vapor present, might make a certain difference in the 

 spectrum; but we are driven to something quite inde- 

 pendent of any change corresponding to quantity. We 

 see that as the temperature is increased the simplicity of 

 the spectrum is increased ; just as a chemist finds with 

 regard to the substances which he has under his control, 

 the func'ion of tempferature is to simplify. Why, then, if 

 this is the result of working with increased temperature 

 here, should not the simplification be due to the breaking 



