NATURE 



\_7unc 7, 1877 



entire Arctic circle, just as the Arctic flora is now ; Asia, Japan, 

 and North-West America being then continuous ; that as the 

 climate became cooler in the pliocene epocli, it was driven 

 southwards along every meridian, its descendants now existing in 

 the localities above mentioned. It will be seen that these form a 

 belt all round the globe, roughly speaking, between the 30tliand 

 40th parallels of latitude. Migration to some extent might have 

 taken place along that belt, but the great migration I suggest 

 was probably from north to south, and not from east to west, or 

 vice versa. 



The above theory is simply an adaptation of that given by 

 Dr. Hooker for a similar dispersion of the existing Arctic flora, 

 which replaced the temperate floras of Europe, Asia, and 

 America ; but which on the return of a temperate climate 

 retreated northwards as well as up temperate and even tropical 

 mountains, perishing, however, in the low lands. 



George Henslow 



The Fertilisation of Orchids 



While botanising this spring in Portugal, I was struck with 

 the fact that scarcely one of the orchids — species of Ophrys 

 principally — that I had collected for my herbarium, or exa- 

 mined in the field, seemed to be fertilised, for none presented 

 the least indication of having had pollen applied to its stigmatic 

 surface ; and I examined flowers in every stage of expansion, 

 from the opening of the bud to the withered and shrunk up floral 

 envelopes. Kach one, I remarked besides, contained its own 

 poUinia, their caudicles in their respective glands and in their 

 natural position. I was so struck with this, that one day 

 (March 31) I gathered and examined forty-five different flower- 

 heads, and of all these only one was found to have pollen-grains 

 on its stigma, and all, the fertilised one included, had their 

 pollinia intact. The locality was the Tapada d'Ajuda, or Royal 

 Park, situated just outside the city walls of Lisbon, an inclosure 

 containing many acres of land, clothed in spring with a rich 

 flora, and a favourite entomological hunting ground, teeming 

 with Coleoptera, Ilymenoptera, and the commoner Lepidoptera. 

 Several of the orchids contained aphides, and a few harboured 

 a species of small red ant. 



On April 21 I again made similar observations, selecting the 

 same place, as it was most accessible to me, and because several 

 orchidea; grew there in the greatest profusion. On this occasion 

 I examined over thirty flowers — none of them the same as I had 

 examined in March, for I had plucked these at the time, but 

 there was not one that did not possess its pollinia, and, as on the 

 previous occasion, none of them showed any appearance of 

 having had pollen-grains in contact with their stigmas. 



Yet the Tapada, during the spring, produces these orchids by 

 the thousand, vigorous, healthy, sweet-smelling plants, and in 

 sunny days its air is perfectly alive with insect life, as I have 

 said, of every kind. Henry O. Forties 



Old Hall, Highgate, N." 



New Meteor Hadiant 



The "two remarkable meteors" closely following each other, 

 observed by Mr. Hope on May 13 (N.\i ure, vol. xvi. p. 43), 

 proceeded most probably from a shower in the small southern con- 

 stellation Crater. Your correspondent describes the point of first 

 appearance as a little south of Arcturus. If this means about 

 7° or 8° below that star, then the observed courses accoril well 

 with the centre indicated, which is apparently quite a new radiant. 

 From the Italian catalogue of 7,512 meteor paths (observed by 

 Schiaparelli, Denza, and others in 1S72) which I have lately 

 been reducing, I found this shower at R.A. 170°, Dec. 10° S. 

 (near € — 9 Crateris) for May 3-15 from nine meteors. 



Ashley Down, Bristol, May 27 W. F. Denning 



OUR ASTRONOMICAL COLUMN 

 Anthelm's Star of 1670.— The small star which is 

 very close to the position of this object, as determined 

 from the observations contained in Lemonnier's " Histoire 

 Celeste," deserves to be closely watched, as there is more 

 than a suspicion of its variation within narrow limits. 

 Thus in August, 1872, it was exactly equal to a star which 

 follows it I2'5s. in R.A., 4''9 to the north; while in 

 November, 1874, it was as certainly fainter by half a 

 magnitude. This small star precedes the variable S. 



Vulpeculas 43'6s., and is north of it 2' 11"; two other 

 small stars follow less than 2' from the parallel, 22-45. and 

 3o"6s. respectively. 



Prof. Schunfeld found the place of Anthelm's star from 

 the observations of Hcvelius and Picard, 



R.A. igh. 41m. 37s. N.P.D. 63" 2''3 for 1855-0. 

 The place of the suspicious star alluded to above is, for 

 the same epoch, 



R A. igh. 41m. 43-5. N.P.D. 63° 2' 7''. 

 It was meridionally observed at Greenwich in 1872. 



D'Arrf.S'i's Comet. — As yet we hear nothing of obser- 

 vations of the short-period comet of D'Arrest, for which 

 M. Leveau has worked so laboriously, with the view to 

 facilitate its discovery at the present return. The inten- 

 sity of light was at a maximum about May 22, but dimi- 

 nishes gradually during the summer. Nevertheless, early 

 in August it is still of the same amount as when Prof. 

 Schmidt discontinued his obser\'ations at Athens in 

 December, 1870, at which time he stated he could have 

 followed it longer but for the want of an ephemeris. 

 Subjoined are the comet's calculated positions during the 

 absence of moonlight in the present month, for Paris 

 noon : — 



Right Norlh Polar Distance froirr 



Though the comet will not arrive at its least distance 

 from the earth during the present visit (1-396) until 

 October 20, it passed its perihelion on May 10. The 

 period of revolution is now 2,434 days, or 35); days longer 

 than at its last appearance in 1870. 



The D'Angos Comet of 1784.— Perhaps no person 

 who has been occupied in astronomical observation and 

 calculation has obtained for himself, rightly or wrongly, a 

 more unenviable notoriety than the Chevalier D'Angos, 

 who, in the latter part of the eighteenth century, was 

 possessed of a small observatory in the island of .Malta. 

 From the unusual character of some of his statements his 

 name came to be associated with anything in the way of 

 observation that appeared to be apocryphal, and wc tind 

 not only Zach was in the habit of terming doubtful asser- 

 tions " Aiij^osiadL-s" but even Pastorff, who himself put 

 upon record more than one suspicious statement, appeared 

 to consider that he was establishing the good faith of an 

 observation of a comet in transit across the sun's disc by 

 declaring that it was not an observation made " ;\ la 

 D'Angos." We pass over on this occasion the reported 

 observations by D'Angos in 17S4 and 1798 of a comet or 

 planet upon the sun, with the view to presenting the reader 

 with a brief outlme of the actual state of a case that has 

 been open to still greater suspicion, viz., his observation 

 and calculation of what appears in some of our catalogues 

 as the second comet of 1784 ; and we may be pardoned 

 for bringing together here particulars which though pro- 

 bably known to those who have access to a good astro- 

 nomical library, arc not so likely to be within the cognisance 

 of those who cannot command such a collection. And fur- 

 ther, it is almost essential to bring the main points in the 

 case into one view, to enable the reader to judge for him- 

 self whether D'Angos is deserving of the opprobrium 

 which has been cast upon him or not. 



Writing from Malta on April 15, 1784, D'Angos apprised 

 Messier at Paris that he had discovered a comet in Vul- 

 pecula on April 11, and he inclosed two approximate 

 positions observed on the mornings of these days. He 

 stated that the comet was very small, without tail, and 

 with only " a slight appearance of nebulosity." Messier 



