NOTES 



ASTRONOMY. 



By A. C. D. Crommelin, D.Sc, B.A. 



COMETS. — Two comets have been found in the last few 

 weeks. One is Wolf's Periodic Comet, a well-known member 

 of the Jupiter family, which was photographically detected by 

 Its original discoverer, Dr. Wolf, when only of the fifteenth 

 magnitude. It was extraordinarily close to the place 

 predicted by M. Kamensky, the error being 0^-5 in R.A., 6" in 

 Decl. This comet will not pass perihelion till February, 1912, 

 and is, therefore, still at a considerable distance from the Sun. 



The other comet is an unexpected one, and promises to be 

 faintly visible to the naked eye. In fact, M. Belopolsky gives 

 its magnitude as 4-0, on July 9th, and states that it had a tail 

 i" in length, in direction 285 ". The comet was discovered on 

 July 6th, by Mr. Kiess, at the Lick Observatory, and will there- 

 fore bear his name. Professor Kobold, of Kiel, has deduced 

 these elements: Perihelion passage. 1911, June 20-64, Berlin 

 M.T., Omega 99° 32', Node 172° 28', Inclination 148° 39', 

 Perihelion distance 0-7932. The comet is now receding from 

 the Sun, but at the same time its position in the sky is 

 becoming more favourable, as it is getting 1A° further from 

 the Sun in angular distance each day, and is also rapidly 

 approaching the Earth, which it will continue to do till nearly 

 the end of August, when it will be distant some thirty-five 

 million miles, and observable for the greater part of the night. 



.\n interesting feature in this orbit is its close resemblance 

 to that of the comet 1790 I, which was discovered by Miss 

 Caroline Herschel in January, 1790, but only seen on four days. 

 When the new comet has been observed for a month or so, it 

 will be possible to decide the cjuestion of identity. Even a 

 close resemblance of orbit is not a proof of identity, for there 

 are several instances of families of comets that travel in 

 practically the same path. The most striking instance is that 

 of the very brilliant comets of 1S43, 1880, 1882, 1887. There 

 can be little doubt of common origin in these cases. 



This generation has probably seen its last of Halley's 

 comet. Professor Barnard followed it visually till May 2+th, 

 and it was photographed at the Lick Observatory till May 27th. 

 It was then outside Jupiter's orbit, and the total period of 

 observation is one and three-quarter years. Doubtless further 

 attempts at photography will be made when it emerges from 

 the sun's rays in the autumn, but their success is doubtful. 



It is likely that the large number of periodic comets that 

 have been visible during the last two years has distracted the 

 attention of observers from the search for new ones. I would 

 suggest this as a promising field for amateurs with leisure for 

 sweeping ; a three-inch telescope with a low-power eyepiece is 

 sufficient equipment ; I think few have seriously taken up 

 this work without success before very long. 



THE EIGHTH SATELLITE OF JUPITER.— In 

 addition to the photograph obtained at Helwan, Egypt, Dr. Wolf, 

 at Heidelberg, and Mr. Innes, at Johannesburg, have succeeded 

 in obtaining images of this seventeenth magnitude satellite. 

 This success is very satisfactory in view of the fact that it will 

 be unobservable at Greenwich till 1915, and gives ground for 

 hope that the interval will be bridged over satisfactorily. 

 A number of minor planets, both old and new, were recorded 

 on the plates. About seven hundred of these little bodies are 

 now definitely numbered, and hundreds more have been 

 observed, but their orbits are not accurately known. The 

 zone shows no signs of exhaustion, and the calculation of their 

 orbits and ephemerides is a severe tax on the Berlin 

 Recheninstitut. 



TOTAL ECLIPSES. — The eclipse of last April was not a 

 complete failure as observed from Vavau and neighbouring 

 islands in the Pacific. Records of the general form of the 

 corona (approximating to the type of sunspot-minimunr) were 

 obtained and we may hope for a few spectroscopic results. 



But evidently the great humidity of the climate was a draw- 

 back, as the fall of temperature caused condensation of vapour. 

 There is a favourable totality in October, 1912, the track 

 crossing Brazil, and emerging a little west of Rio. It is 

 expected that two parties will go from this coiintry to view it, 

 and doubtless other nations will be represented. In April. 

 1912, there will be totality for a second or two in Portugal 

 and N.W. Spain. It will be a particularly favourable occasion 

 for obtaining impressions of the reversing layer all round the 

 sun, and it should be possible to photograph the inner corona 

 with rapid plates. Great care will be required in selecting 

 a station, its accurate longitude and latitude must be 

 known, as the track of totality is less than a mile broad. 

 Those who desire to witness the eclipse as a spectacle without 

 doing serious work may go to the north-west outskirts of Paris. 

 There will not be absolute totality there, but I anticipate that 

 there will only be a few small patches of sunlight through 

 depressed portions of the moon's limb, not a complete ring. 

 This eclipse is a return after the triple Saros of that of 1858, 

 the last central eclipse in the British Isles. The next will be 

 1921 (annular, Hebrides and Shetlands) and 1927 (total 

 across Wales and England). 



BOTANY. 



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



ORIGIN OF CHLOROPLASTS IN SEEDLINGS.— 

 Two widely divergent views have been held with regard to the 

 origin of chloroplasts (chlorophyll grains) in seedlings. 

 According to one \iew. the chloroplasts originate directly 

 from the general protoplasm of the cell, the mature seed itself 

 containing no chloroplasts. Another group of investigators 

 maintains that the protoplasm of the cell never gives rise to 

 chloroplasts, but that the fertilised egg contains plastids 

 derived directly from the parent plant, and that during 

 development of the egg these multiply and thus provide every 

 cell of the embryo with chloroplasts. 



.According to Sachs, the chloroplasts arise in the young cells 

 by the separation of the protoplasm into portions which 

 remain colourless and others which become green and sharply 

 defined. He held that the process takes place by very small 

 particles, originally of a different nature from the apparently 

 homogeneous protoplasm in which they are distributed, 

 collecting at definite places and appearing as separate masses. 



Mikosch, after examining the seeds and seedlings of the 

 sunflower, concluded that there are no plastids in the resting 

 seed, but that during germination the chloroplasts arise 

 directly from the protoplasm of the cells, owing to condensa- 

 tion of the protoplasm in definite places, this condensation 

 being probably due to loss of water in these parts, which soon 

 become green. The process occurs independently of light, 

 and the bodies thus formed are at first rod or spindle shaped, 

 but later assume the typical disc shape of the chloroplasts. 



Belzung, after a long investigation of the ripening seeds, 

 mature resting seeds, and seedlings of many plants, came to 

 the following conclusions : (11 the free growth of starch grains 

 can take place without the intervention of plastids; (2) the 

 chloroplasts are formed directly by dift'erentiation of the 

 protoplasm; (3) the chloroplasts can also be formed at the 

 expense of the starch grains which have their origin in the 

 protoplasm of the cell. According to Belzung, the young 

 embryo contains no chloroplasts, the starch grains formed in 

 it are laid down in vacuoles of the protoplasm, and the green 

 colour of the embryo in many plants is due to green pigment 

 distributed through the protoplasm. No chromatophores are 

 present in the embryo, consequently there are none in the 

 mature seed. At germination the simple starch grains of the 

 seed disintegrate, and numerous compound grains of transitory 

 starch appear in various parts of the protoplasm. Each large 



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