September lo, 1903] 



NA TURE 



461 



think that we see here a new species arise by the produc- 

 tion, through many generations, of an increasing number of 

 individuals (ruja forms) among the offspring, that are 

 markedly unlike the parents {austriaca forms). We believe 

 that austriaca forms give rise to rufa forms, but we have 

 JO evidence of the reverse process." 



At the conclusion of the second part of his memoir on 

 the development of the molluscan lingual ribbon, or radula, 

 Mr. H. Schnabel, in the Zeitschrift fiir wissenschaftliche 

 Zoologie, vol. Ixxiv. part iv., points out an important dis- 

 tinction in this between cephalopods and gastropods. In 

 contrast to the cephalopods, the development of the radula 

 in the gastropods commences, not with the appearance of 

 the single unpaired median row of teeth, but with a number 

 of paired lateral rows. The other contents of the issue in- 

 clude an article on gastrulation in Cucullanus, by E. 

 Martini ; an essay on the morphology of the male genital 

 appendages of the Lepidoptera, by E. Zander ; and an 

 account of the structure of the bristles in certain chaetopods 

 and brachiopods, by A. SchepotiefT. 



The alleged occurrence of " aptosochromatism," that is, 

 colour-change in feathers without moulting, in birds, has 

 by no means met with universal acceptation, one at least 

 of the late Mr. F. J. Birt well's three papers on this subject 

 having been adversely criticised. Shortly before his death 

 Mr. Birtwell entered on a fresh series of observations in 

 the hope of establishing his theory on a basis which would 

 be beyond question. These observations, which were made 

 on two species of buzzard, are now published in the Bulletin 

 of the Hadley Laboratory of the University of New Mexico 

 (vol. iii. No. 7). 



An Irish specimen of Dopplerite has been described by 

 Mr. Richard J. Moss (Set. Proc. Royal Dublin Soc, vol. x. 

 No. 6). It was found in peat in Sluggan bog, at Drumsue, 

 near Cookstown Junction, in County Antrim. In its 

 original moist condition it appeared like a stiff jelly of a 

 velvety-black colour, but when dry it became very like jet, 

 breaking with a conchoidal fracture, and exhibiting a 

 vitreous lustre. Dopplerite was originally found in peat 

 in Styria, and has not previously been recorded from Britain. 

 It appears to have been formed from peat by a process of 

 oxidation. 



A HANDBOOK to Southport, which should prove of much 

 service to those attending the meeting who are not well 

 acquainted with the town, has been written for the 

 members of the British Association. Southport is con- 

 sidered from a historical and descriptive point of view, and 

 as a health resort. Other chapters are devoted to meteor- 

 <^'f g'y. Reology, botany, zoology, Martin Mere, archaeology, 

 and the life and works of the Rev. Jeremiah Horrocks (spelt 

 in the volume Horrox). The volume is published by Messrs. 

 Fortune and Chant, of Southport, and appears to have been 

 carefully prepared. 



The current issue of the Illustrated Scientific News is a 

 double one, and brings to a close our contemporary's first 

 volume. The number contains many interesting articles, 

 among which there are no fewer than three respecting the 

 British Association ; one is illustrated by portraits of the 

 president and five of the presidents of sections for this year. 

 Other contributions deal with " Charlottenburg, " the 

 " Solar Physics Observatory at Meudon," " Progress with 

 Airships," &c. 



The additions to the Zoological Society's Gardens during 

 the past week include two Black Rats (Mus rattus), British, 

 NO. 1767, VOL. 68] 



presented by Mr. J. E. Millais ; a Ducorps's Cockatoo 

 (Cacatua ducorpsi) from the Solomon Islands, presented by 

 Mrs. J. Aarons ; a Neumann's Baboon (Papio neumanni), a 

 Doguera Baboon (Papio doguera) from Abyssinia, a Bell's 

 Cinixys (Cinixys helliana) from Tropical Africa, an Adan- 

 son's Sternothere (Sternothoerus adansoni) from North-east 

 Africa, deposited ; three Fat-tailed Desert Mice (Pachuromys 

 dupresi), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Search-ephemeris for Faye's Comet. — In No. 3896 of 

 the Astronomische Nachrichten, Herr E. Stromgren gives 

 a continuation of the search-ephemeris for Faye's comet 

 which appeared in No. 3876 of the same periodical, and 

 was reproduced in these columns. The following is an 

 extract from the later portion : — 



1903 



Ephemeris I2h. {M.T.Berlin). 



a. S log : 



lORA 



Sept. 12 ... 8 5 14 ... +12 I3*4 ... o'2842 ... 0.3864 



,, 16 ... 8 13 26 ... +11 34-8 ... — ... — 



„ 20 ... 8 21 24 ... +10 55*5 ... 0-2930 ... 0-3821 



„ 24 ... 8 29 6 ... +10 15-5 ... — ... — 



„ 28 ... 8 36 31 .. +9 35-1 ... 0-3020 ... 0-3771 



Oct. 6 ... 8 50 32 ... + 8 134 ... 0-3110 ... 03712 



„ 14 ... 9 3 28 ... + 6 51-6 ... o*32or ... 0*3645 



„ 23 ... 9 15 15 ... + 5 30-7 ... 03293 ... 03569 



„ 30 ... 9 25 48 ... +4 II -8 ... 0-3384 ... 0-3484 



The Canals on Mars. — In the fifth report of " The 

 Section for the Observation of Mars " (British Astronomical 

 Association Memoirs, vol. xi.), several charts of the planet's 

 surface are reproduced, in one of which, Plate viii., the 

 director of the section, M. E. M. Antoniadi, has omitted 

 the reticulated canal systems so familiar to aerographers 

 on the charts published during the last twenty-five years. 

 These have been omitted because recent research has thrown 

 grave doubts on their objective reality. 



In the recent experiments carried out by Messrs. Maundei 

 and Lane it was demonstrated that the regular " canali- 

 form " markings may be consistently seen by numerous 

 unbiased individuals on a surface which is free from any 

 such markings, but which has drawn on it features similar 

 to the other markings on Mars. It was also pointed out 

 that, in general, the so-called canals on aerographical maps 

 are drawn either from one projecting feature to another or 

 where half-tone boundaries are seen on the planet, just 

 where one would expect them to be drawn if they were really 

 due to physiological suggestion. 



Many so-called " canals " are retained on M. Antoniadi 's 

 chart, but these are not of the rigidly geometrical shape 

 shown on the charts published during recent years, and are, 

 probably, objective features of the Martian landscape (the 

 Observatory, No. 335). 



Radiation Pressure and Cometary Theory. — In No. 5, 

 vol. xvii., of the Astrophysical Journal, Messrs. E. F. 

 Nicholls and G. F. Hull describe and illustrate some 

 laboratory experiments they have made at Dartmouth 

 College, Hanover, U.S.A., in order to demonstrate the effect 

 of the solar radiation pressure in the formation of comets' 

 tails. 



A glass tube shaped like an hour-glass was partially filled 

 with sand and dried lycopodium powder, and then highly 

 evacuated. On causing the sand and powder to fall from 

 the upper to the lower part of the .tube, and directing an 

 intense beam of light against the stream, it was seen that, 

 whilst the sand fell vertically, the powder was diverted in 

 the direction of the beam against the side of the tube 

 opposite, to the light source. Unfortunately the light 

 pressure, on particles of the size and density used, had been 

 previously overestimated, and a subsequent calculation 

 showed that the observed deviation may not have been 

 wholly due to the light-pressure, although some of it was. 



Another suggestion as to the cause of repulsion in 

 cometary phenomena is that the particles heated from one 

 side evolve gases, and are, therefore, driven in the opposite 



