\o'ri-:s. 



.\SIk()\()M\'. 



By A. C. D. Crommelin, B.A., D.Sc, F.R.A.S. 



PROFESSOR TLIRNRR'S SL'GGESTED EXPLANA- 

 TION OF THE TWO STAR-DRIFTS.— Professor Turner 

 contributed papers to the March and April numbers of The 

 Monthly Xoticcs, maliing a new suKKCstion to explain the 

 apparent division of the stellar motions into two drifts. It has 

 generally been assumed that a drift converging to or diverging 

 from an apex (like a meteor radiant) indicates a series of 

 motions along parallel paths. But Professor Turner reminds 

 us that the same result would follow from an actual 

 convergence of motion to a point and divergence from it. He 

 suggests that the stars may be moving in very elongated orbits 

 about the centre of the sidereal system, so that at any moment 

 they may be divided into those moving inwards and those 

 moving outwards. He gives, as an analogy, the system of 

 comets moving round the sun : at any instant practically all of 

 them are moving either nearly to the sun or nearly from it. 



Sir John Herschel, in the " Outlines of .Vstronomy," briefly 

 discussed the case of motion in spherical star clusters. 

 Assuming the density of distribution as uniform, it is easy 

 to see that the attraction towards the centre of the cluster is 

 as the direct distance, and hence the stars would all describe 

 ellipses in the same time about the centre. In actual clusters 

 the density is not uniform ; Mr. Plummer suggests a law of 

 density found by Schuster for gases, vi^., |c"+r") ?, where r 

 is the distance from the centre and c isa constant. The form 

 of the actual sidereal system appears to be ellipsoidal, and the 

 density not uniform, so that the orbits would not be strictly 

 ellipses, nor would the periods be the same for all stars. 

 Professor Turner fixes the vertex at R.A. 94°, N. Dec. 12° as 

 the probable centre of the system, and shows that this agrees 

 very well with the centre I R.A. 113°. N. Dec. 22°) found by Mr. 

 Lewis from the distribution of apparently fixed and moving 

 binary systems. He suggests that our Sun was near the centre a 

 million years ago, and that the period of a complete oscillation 

 is about four hundred million years, the semi-axis major of the 

 orbit is about six hundred light years. The crowding indicated 

 near the centre is such that the distance between neighbouring 

 stars there is half that from the Sun to Alpha Centauri. 



While there is nmch that is highly speculative in these papers, 

 they are interesting as an attempt to coiirdinate the results of 

 a great many different series of observations, and as giving a 

 readily intelligible meaning to the two stellar drifts. 



Mr. Eddington has also a paper on star distribution in the 

 March number of Monthly Notices. He gives a diagram of 

 velocity distribution that brings out the two drifts very forcibly, 

 and suggests a third drift. Deducing the distances of stars 

 from their proper motions, he gives the following table of the 

 average parallaxes of the stars in Boss's Catalogue (that is, 

 roughly, the stars visible to the naUed eye). Out of one 

 hundred naked eye stars he finds that 1-0 has a parallax 

 between "-10 and "-08, 1-5 between "-08 and "-06, 2-9 

 between "-06 and "•04,9-5 between "-04 and "-02, 8-6 between 

 "•02 and "-015, 17-5 between "-015 and "•OlO, 11 •? between 

 "•010 and "-008, 14-9 between "-008 and "-006, 16^6 between 

 "•006 and "-004, 10-0 between "-004 and "^002, 2-4 between 

 "•002 and "•OOl. Of course, the falling off at the end is due 

 to the fact that at great distances stars must be of extra- 

 ordinary lustre to be visible to the naked-eye, so that only a 

 few of the naked-eye stars lie in these distant regions. 



PLANET MT. — In addition to the Greenwich observations 

 of this body on October 11th last, traces of it have been 

 found on a plate taken at Heidelberg on (Jctober 17th. The 

 following elements are rough, but give a general idra of the 

 character of the orbit. 



Perihelion Passage, 1911, August 31st. 



Node ... ... ... ... 183' 27' 



w ... ... ... ... ... 151 27 



/ ... ... ... ... ... 8 32 



Period ... ... ... ... 2^6 years 



Eccentricity ... ... ... ... 0^40 



Perihelion I)istance, 1-15, practically the same as that of Eros. 



The eccentricity is, however, much greater, and is almost 



the greatest known for planetary orbits. 



BOT.AXV. 



By Professor F. Caveks, D.Sc, F.L.S. 



POTASSIUM AND PHOTOSYNTHESIS.— At the con- 

 clusion of a paper on the photochemical synthesis of 

 carbohydrates from carbon dioxide and hydrogen, Stoklasa 

 and Zdobnicky (Biochetn. Zeitschr., Band 30, 1911) state 

 that their experiments have given the following somewhat 

 remarkable results. Neither formaldehyde nor carbohydrates 

 are formed by action of ultra-violet light on water and carbon 

 dioxide in absence of potash : but if potash be present, 

 formaldehyde is produced, without formation of carbohydrates. 

 By the action of ultraviolet rays on carbon dio.xide and 

 hydrogen, in presence of potash, neither formaldehyde nor 

 carbohydrates are formed unless the hydrogen is in the 

 nascent condition — in which case sugars are produced ; with' 

 out the action of these rays, carbon dioxide and nascent 

 liydrogen produce, in presence of potash, formic acid but not 

 carbohydrates. This is the first case observed of the 

 synthesis of sugar from potassium bicarbonate and nascent 

 hydrogen. The writers suggest that in the living green cells 

 of plants the water and carbon dioxide, under the action of 

 potassium bicarbonate, produce formaldehyde, which is then 

 condensed into sugar in the presence of potash. The interest 

 of these observations lies in the importance attached to 

 potassium as an essential factor in the synthesis of carbo- 

 hydrates from water and carbon dioxide in the living green 

 cell. 



LIFE CYCLE OF RED ALGAE.— The cytological obser- 

 vations of Yamanouchi on Polysiphotiia, Lewis on Griffithsia. 

 and Svedelius on Delcsseria, suggest that not only in these 

 genera but in all Red Algae in which the tetraspores and 

 sexual organs are regularly borne in separate plants, there is 

 an alternation of generations, the germinating carpospores 

 giving rise to asexual plants, and the germinating tetraspores 

 to sexual plants. Lewis has now (Bot. (laz.. LI II.) succeeded 

 in testing this matter by actual cultivation of the sporelings of 

 a number of Red .Algae, though it has proved a difficult task 

 to raise the young plants. The physiological tolerance of 

 these Red Alga sporelings is very small ; temperature, light, 

 and other factors may vary only within very narrow limits. 

 The cultures had to be transferred to the open water, and 

 many precautions taken to ensure their further growth. 



Successful cultures showed that in PolysipliottiiJ the carpo- 

 spores produced only tetrasporic plants ; while from the 

 tetraspores of Grif/ithsia and Dasya only sexual plants were 

 obtained. Tetraspores from a single individual produced 

 male and female plants in .approximately equal numbers in 

 Griftithsia ; the preponderance of males found in the cultures 

 of Dasya is explained by the early development of the sexual 

 organs on these as compared with the fem.ales. This segre- 

 gation of the sexes in equal numbers agrees with what 

 has been found in dioecious liverworts and other plants. 

 Lewis obtained no evidence whatever that the double 

 number of chromosomes in the carpospores imparts greater 

 vigour of growth as compared with the single number in the 

 tetraspores. 



