January 20, 19 10] 



NATURE 



349 



spheric conditions, it was quite inconspicuous even with 

 the full aperture. Again, on December o, with a very 

 clear and transparent sky, he was unable to see the cornet 

 with the aperture at 43 inches, and he estimates that its 

 magnitude was not greater than 11-5 or 12-0; but on 

 December S it was again brighter, the magnitude being 

 estimated to be about 105 or ii^o. 



On January 28-1 the comet will be in conjunction with, 

 and 3° 48' north of, Saturn ; its conjunction with Mars 

 occurred on January J5, when the actual distance 

 separating the two bodies, about 37 million miles, was at 

 its minimum value. 



In a letter to the Times of January 14, the Earl of 

 Crawford points out that for ages the sudden appearance 

 of a great comet has been held to herald some great 

 disaster or revolution. This view of the matter may still 

 appeal to the native races of such countries as Morocco, 

 Egypt, or India, where considerable unrest already pre- 

 vails, and might be used by fanatical agitators to stir up 

 further trouble. He suggests that the communication of 

 a series of popular articles, written in the vernacular, to 

 the native Press, might be beneficial. By announcing and 

 welcoming the appearance of the comet, such articles would 

 forestall the potential mischief-makers and render futile 

 their possible announcements of supernatural manifesta- 

 tions. 



The Spectra of Comets' Tails. — The observations of 

 Deslandres, Evershed, Chretien and others showed that 

 in the spectra of the tails of Daniel's and Morehouse's 

 comets there were certain radiations which were feeble in 

 the heads but extended to considerable distances in the 

 tails of those comets ; the wave-lengths of the three 

 strongest bands were about 402, 426, and 455, but no terres- 

 trial origin could be found for them. 



This has now been done by Prof. A. Fowler, who has 

 succeeded in reproducing them terrestrially in the spectrum 

 of the glow from vacuum tubes which were known to 

 contain carbon compounds at extremely low pressures, 

 001 mm. or less. Further experiments are necessary to 

 determine what particular form, or compound, of carbon 

 is involved, but from the wave-lengths and the reproduc- 

 tions of the spectra published in No. 2, vol. Ixx., of the 

 Monthly Notices there can be no doubt that Prof. Fowler 

 has succeeded in reproducing, in his laboratory, the con- 

 ditions which obtained in the tails of the two comets 

 mentioned above. 



Two Curiously Similar Spectroscopic Binaries. — 

 When Messrs. Plaskett and Harper, of the Ottawa 

 Observatory, published the determined orbit of the spectro- 

 scopic binary t Orionis, the apparent presence of a 

 secondary disturbance was not discussed, because the lines 

 of the spectrum are too diffuse to justify any final con- 

 clusions ; but the recent determination of the orbit of 

 another binary, B.D. — i°.io04, showed that a similar case 

 of secondary disturbance appeared there, and it was 

 deemed desirable to make refined least-square solutions for 

 both orbits. 



The results show that the two binaries are remarkably 

 alike. Both are in Orion, within 5° of each other, and 

 both are helium stars; the periods are 29-136 and 27-160 

 days respectively, and the eccentricity of both orbits is 

 abnormally high (0-74 and 0-76) for spectroscopic binaries. 

 Other features are also very similar, but the most striking 

 similarity is in the secondary disturbances, which are 

 almost identical in period, amplitude, and phase. The 

 period of the secondary in each case is the same as the 

 period of the primary, a novel feature in spectroscopic 

 binaries. It seems probable that the same physical cause 

 is operative in both cases, but what it is is difficult to sav ; 

 the orbital revolution of the system, produced possibly by 

 a resisting medium or by tidal action, is tentatively 

 suggested (Astrophysical Journal, vol. xxx.. No. 5, p. 373). 



The " Annuaire Astronomique, " Belgium. — The 

 " Annuaire Astronomique." for iqio, of the Royal Observa- 

 tory of Belgium contains, besides the usual tables, 

 ephemerides, &c., a number of useful notes and diagrams; 

 among the latter is a coloured chart showing the official 

 standard times of various countries. A list of observa- 

 tories is also given, and special articles are contributed by 

 various members of the staff of Uccle Obscrvatorv. 

 NO. 2099, VOL. 82] 



THE EVOLUTION OF THE BRAIN.' 



AS the result of the investigations carried on in the 

 Museum of the Royal College of Surgeons during 

 the last seventy-five years by its conservators and those 

 who have drawn their inspiration, directly or indirectly, 

 from the work done in the museum, it has become possible 

 to establish on a firm basis the criteria for instituting 

 exact comparisons of the structure of the brain in the 

 various groups of Vertebrata. 



This analytical work has now been carried far enough 

 to justify us in attempting a synthesis of our knowledge 

 of the evolution of the cerebral cortex. The special aim 

 of such a research is to investigate the nature of the factors 

 and the circumstances which have brought into -being the 

 neopallium, the part of the nervous system which, more 

 than any other, is responsible for the kaleidoscopic mani- 

 festations of psychical activities, and the possession of 

 which has made the Mammalia what they are, and given 

 them the dominant position in the animal kingdom. 



At the very root of the Vertebrata we find that Petro- 

 myzon has a cerebral hemisphere no larger than the 

 olfactory bulb of which it is little more than an appendage. 

 Direct nerve tracts pour smell-impressions into almost every 

 part of the surface of this hemisphere. The cerebrum at 

 its commencement is thus almost purely an instrument for 

 the reception and the conscious appreciation of stimuli 

 evoked bv odoriferous particles, and, in the second place, 

 for providing the means whereby the physiological pro- 

 cesses underlying this state of consciousness may aflfect the 

 rest of the nervous system, and through it influence the 

 behaviour of the lamprey itself. It is just possible that 

 even in this lowly vertebrate gustatory fibres brought^ up 

 to the lobus inferior (of the fore-brain) from the terminal 

 nuclei of the seventh and ninth nerves may make their 

 way into the primitive cerebral hemisphere, but it is still 

 uncertain whether the lobus inferior itself may not be 

 the place where impressions of smell and taste meet. 



Even in Petromyzon there is some indication of a 

 differentiation of the hemisphere into a superficial cortical 

 layer (tuberculum olfactorium) and a deeper ganglionic part 

 (corpus striatum), and there is also some slight trace 

 at the extreme dorso-mesial edge of the presence of a small 

 rudiment of the pallium. The tuberculum olfactorium in 

 the Selachii assumes a definite cortex-like arrangement of 

 cells, and is now recognisable as one of the receptive 

 apparatus for olfactory impulses coming directly from the 

 olfactory bulb. The corpus striatum does not receive any 

 direct olfactory fibres ; it is the part of the hemisphere 

 which receives afferent fibres from the tuberculum olfac- 

 torium, and possibly also from more caudally situated 

 regions of the brain — almost certainly gustatory fibres from 

 the lobus inferior — and it emits efferent fibres, which pass 

 to the hypothalamus and indirectly influence the executive 

 mechanisms of the body, i.e. its functions find expression 

 in the behaviour of the animal. 



In some of the Selachii the dorsal part of the hemisphere 

 is definitely transformed into a cortical area or formatio 

 pallialis. In Petromyzon there is still room for doubt as 

 to the existence of any such structure, but when we turn 

 to the study of the brain in some of the sharks there can 

 be no doubt of the existence of a considerable area of 

 primordial pallium. There is every reason to believe that 

 this pallinl formation represents the undifferentiated rudi- 

 ment of the whole pallium of the higher vertebrates. Its 

 mesial edge ultimately becomes specialised to form the 

 hippocampus, which in the higher Vertebrata does not 

 receive smell-impulses directly from the olfactory bulb, but 

 indirectly through the intermediation of the olfactory 

 peduncle and tuberculum olfactorium on the mesial side, 

 and of the pyriform on the lateral side. The lateral edge 

 of the pallium eventually develops into the pyriform lobe, 

 which continues to receive olfactory impressions direct from 

 the bulb. Much later on, only, in fact, when the mammal 

 appears on the scene, the pallial area intervening between 

 the hippocampus and the pyriform lobe becomes specialised 

 to form the neopallium. It is only right to say that this 

 view of the nature of the primitive pallium differs funda- 



I Summai-v of Three " .'\rr;s and Gale Lectures" on "Some Problemsi 

 relating to the Evolution of the Brain," delivered in the Royal College of 

 Surgeons on December 13. 15, and 17, 1909, by Prof G- Elliot Smith 

 F.R.S. 



