December, 1901.] 



KNOWLEDGE. 



277 



Astronomical. — Prof. Campbell has recently pub- 

 lished fiu'ther details of the system of Capella. which 

 was recognised as a spectroscopic binary by !Mr. Newall 

 and himself independently. (Lick Obs. Bull., No. 6.) 

 The principal st<»r hiJd a spectnim of the solar type, 

 and its velocity ranges from +4.- to +55.7 km. per 

 second, while the companion has a spectrum between 

 the solar and Sirian types and a velocity in the line of 

 sight ranging from — 3 to +63 km. per seeond. The 

 masses of the two components are therefore as 1.26 to 1, 

 but for various reasons, the masses in terms of the sun 

 are as yet indetenninate. The orbit is neai'ly circular, 

 the period 104 days, and the whole system is receding 

 from the sim at the rate of '2.5'76 kilometres per second. 

 As the inclination of the orbit cannot be determined 

 with the spectroscope, the actual size of the system 

 remains unknown, but with the smallest permis-sible 

 orbit, the two stars will be 85,000,000 kilometres apart 

 when most dista,nt from each other. So far, even under 

 the most favourable conditions, the Lick telescope has 

 failed to show any indications of the binary character 

 of the star. The latest investigations of the spectro- 

 scopic binary"') Pegasi indicate for this star a period of 

 818 days (Bulletin No. 5). 



As was to be expected, a very valuable set of obser- 

 vations of Nova Persei has been secured at the Lick 

 Observatory (Bulletin No. 8). The position of the star 

 has been carefully determined by meridian obsei-vations 

 and by micrometric measuies, and a long series of 

 estimates of magnitude have been recorded. Extensive 

 spectroscopic observations have also been made, and the 

 high dispersion employed has revealed much minute 

 detail which may perhaps turn out to be of great im- 

 poi-tance. Among the more important results, it 

 appears to have been established that the velocity of 

 the Nova, as indicated by the fine dark line super- 

 posed upon bright H has been practically constant 

 and very small, up to September. At present the 

 spectrum is nebular, an additional demonstration of 

 this being furnished by the discovery that the Nova 

 line near Hj occurs as a line at >. 3967-6 in N.G.C. 

 7027, and that the strong ultra-violet line about A364 

 also appears in some of the well-known nebulae. It is 

 the last named radiation which probably causes the 

 spurious aureole surrounding the photographic image of 

 the Nova as depicted by a refractor. 



From the Lick Obsei-vatory comes the startling 

 announcement that four nuclei in the true nebula in 

 "which Nova Persei is involved have been displaced by 

 a minute of arc in six weeks. 



One of the most remarkable stars in the heavens is 

 i; Argils, which between 1677 and 1870 fluctuated 

 between magnitude and 68 and has since faded to 

 7j. It has long been known that the spectrum was an 

 uncommon one, and recent photographs taken by Sir 

 David Gill show that it is full of bright lines which are 

 apparently similar to those of Nova Aurigse and Nova 

 Pcraci in their earlier stages. Dr. F. McClcan has 

 already drawn attention to the fact that the spectnim 

 is practically a reversal of the pectrum of a Cyg^i. — A. F. 



Botanical. — The well-known fairy rings met with ou 

 oiu' lawns and pastures are produced by various species 

 of Fungi, most frequently by Marusmius oreaden. In 

 North America it has been obsei-ved that similar 

 peculiarities of growth are affected by other plants 

 besides Fungi. In Rlmdura Dr. Robinson cites the case 

 of one of the club mosses, I.ycDiiixliuin iniiiHhituiii. He 

 attributes the rings to the plants moving outwards from 

 the centre in search of fresh soil and new food supplies. 

 Mr. W. N. Clute in the October number of the Fern 

 Bulhtin records instances of rings formctl by species of 

 O^tinnula. and conjectures that these rings have taken 

 at least a hundred yeai-s in their formation. Monanla 

 didynia, a Labiate often seen in British giudens, is also, 

 according to Professor Beal, a producer of fairy rings. 



The origin of the eminently useful cocoanut palm, 

 like that of several other valuable economic plants 

 which have been in cultivation for very long periods, is 

 still disputable. Do Candolle, in his Oriijiii of cidti- 

 rated />l/in/.i, expressed the opinion that, though he 

 formerly thought that the arguments in favour of 

 Western America were the strongest, a more extended 

 study of the subject inclined him to the idea of its 

 origin being in the Indian Archipelago, a view which 

 received the support of many celebrated naturalists. 

 Mr. O. F. Cook has been dealing with the question in 

 the recently issued number of the Coiitrilmtions from 

 the U.S. Xut/onal Herhariuiii. and arrives at the con- 

 clusion that the original habitat of the palm is to 1x; 

 sought in South America, the probabilities favouring 

 the alkaline regions of the Colombian Andes. It is 

 pointed out as a forcible argument that all the other 

 known species of Coco.s are natives of South America, 

 and no other genus of palms is common to America 



and Asia or Polynesia. — S. A. S. 

 — *-*-t — 



Entomological. — Both on account of the interest of 

 their habits and of their importance from an economic 

 standpoint, the gall-midges (Cecidomi/iirla') are worthy 

 of more attention than they usually receive from 

 naturalists. Their small size makes their study very 

 difficult. Specially accejitable therefore is the recent 

 issue of the Abbe .1. .1. Kieffer's " Monogiaphie des 

 Cecidomyides d'Europe et d Algerie," in the Ann. Ent. 

 Sac. France, Vol. LXIX,, 1900, pp. 181-472, pis. 15-44. 

 This work includes a very full bibliography, a detailed 

 account of the anatomy of the midges and their larvae, 

 a summai-y of the vei-y various ways in which the latter 

 feed in different plant tissues, each causing its 

 characteristic gall, and a systematic account of the 

 genera into which the family has been divided. The 

 species of economic importance — the dreaded " Hessian- 

 fly " of wheat and the " Pear-Midge " are well-known 

 examples — are dealt upon at length, and the natural 

 and artificial means of checking tlieir ravages are 

 pointed out. Among our helpers in the destruction of 

 these injurious insects are to be reckoned bii-ds, spiders, 

 insects (chiefly parasitic Hymeuoptcra), and minute 

 thread-worms, which live inside the Cecidomyids in both 

 larval and perfect stages. 



From notices in the various entomological journals, 

 the year 1901 seems to have been remarkable for the 

 great abundance of Hawk-motlis in the British Isles. 

 Records of the " Deaths-head " (Athtruntia atropos) 

 and of the Convolvulus Hawk-moth (Protiqiarce con- 

 fiilvuli) have been plentiful, and the latter insect seems 

 to have bred freely with us, as caterpillars have occurred 

 in Scotland and Ireland, as well as in England. The 

 green fomi of tiie caterpillar — a marked contrast to the 

 brown type — has been noted in several localities. 



