September, 1910. 



KNOWLEDGE. 



363 



situated about four degrees South- East of the star o Geniinoruui. 

 Meteors : — 



Minima of Algol occur on the ISth at 12.35 a.m., the 20th 

 at 9.24 p.m., and on the 23rd at 6.13 p.m. The period is 

 2'' 20*" 49™, from which other minima mav be calculated. 



Telescopic Objects: — 



Double Stars.— f Ursae Majoris XIII.'' 20", N. 35 25'. 

 mags. 2, 4 ; separation, 14""4. 



^'A<inani XXII.'' 24'", S. 0° 32'. mags. 4, 4; separation, 

 2""9. Both components are yellowish. 



/3 Cygni XIX." IT", N. 27° 46', mags. 3, 5 ; separation, 34" 

 The brighter component is yellow, the other blue ; very easy 

 double in small telescopes with a power of 20. 



Cluster iM 111 in Aquila or Antinous. R.A. IS'' 46'"; 

 Dec. S. 6° 23'. Very pretty object for three or foiu'-inch 

 telescopes ; it is an easily resolvable fan-shaped cluster, with 

 an eighth magnitude star in apex, and an open pair of the 

 same magnitude just outside it. 



NOTES 



ASTRONOMY. 



By G. F. Chambers, F.R.A.S. 



HALLi:VS COMET AS SEEN IN SOUTH AFRICA.— 

 The following account, dated May 16th, 1910, of Halley's 

 Comet as it appeared in Cape Colony, has been sent bv 

 Mr. H. R. Butcher:— 



Your readers may be interested to hear that Halley's Comet 

 presented a magnificent appearance this morning, viewed from 

 an elevation of over four thousand feet above sea level. 



Owing to the fact that the Comet is south of the sun, it can 

 be best seen in the southern hemisphere, and the exceptional 

 clearness of the atmosphere on the Karoo plains of South 

 Africa renders our position a particularly favoui'able one for 

 observing the Comet during its present return. 



The Comet was first visible here to the naked eye on 

 April 13th, and, at its perihelion passage, appeared with a tail 

 of about 2i°. By May 1st the Comet had increased con- 

 siderably both in size and brightness, and I estimated the 

 length of the tail on that date at 8°. 



On May 9th the Comet was a striking object, the nucleus 

 being about equal to a second mag. star, and the tail. 18° in 

 length. 



Since May 10th, owing to the swing of the Cornet towards 

 the earth, there has been a rapid increase in brilliance and in 

 the apparent length of the tail. Although the head of the 

 Comet is rapidly receding towards the sun, the tail reaches 

 higher and higher each morning into the sky. 



This morning the nucleus rose at 5 a.m., two hours before 

 sunrise, and as the planet " Saturn " rose at exactly the same 

 time a few degrees further south, I was able to obser\e the 

 relative brightness of the two objects. The diameter of the 

 Comet's nucleus was considerably greater than that of the 

 planet, but it shone with a duller light, and lacked the 

 brilliance of Saturn. That the brightness of the two objects 

 was almost exactly equal is proved by the fact that, as the 

 daylight increased and stars faded, the nucleus and the planet 

 became invisible, almost simultaneously, half an hour before 

 sunrise. The tail presented a most striking appearance at 

 5.10 a.m. It appeared to be perfectly straight, but broadened 

 gradually from the head. It could be distinctly traced for a 

 distance of 55° from the head, reaching to the border of the 

 constellations Aquarius and Pegasus about R.A. 22*" and 

 Decl. 3° North, whilst the position of the nucleus was about 

 R.A. 1" 40'". Dec. 15° North. A fourth magnitude star, 

 presumably " '; Piscium," could be seen shining through the 

 densest part of the tail without any apparent enfeebling of its 

 brilliancy. 



With regard to the supposed connection between Halley's 

 Comet and the Aquarid Meteors, referred to by Mr. W. F. 

 Denning in the April number of " Kxowledge." it is reported 

 that a fine shower of meteors and one remarkably large fire- 

 ball were observed from Cape Town on the morning of May 



7th. The sky was, unfortunately, cloudy here on that date, but 

 I have observed small meteors, coinciding with the Aquarid 

 radiant point, almost every morning since May 1st, but only 

 perhaps half-a-dozen in an hour's time. On several mornings 

 also I observed meteors whose radiant point coincided with 

 the tail of Halley's Comet, so that they appeared to fall out of 

 the tail. 



BOTANY. 



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



TOXIC SOLUTIONS AND NUCLEAR DIVISION.— 

 Stockborger ( Bof. Gaz. ) has just published an interesting 

 paper, dealing with the influence of poisonous solutions upon 

 the process of nuclear division or mitosis. Some of his results 

 differ markedly from the accounts gi\ en by previous workers 

 in this field. For instance, Stockberger claims (1) that the 

 toxic substances (copper sulphate, phenol, strychnin) with 

 which he treated the roots of broad-bean seedlings did not in 

 any case produce direct nuclear division (amitosis) ; (21 that 

 doubling of the nucleolus is not a preparatory stage of amitosis, 

 as stated by Wasielewski ; (3) that no structures were found 

 corresponding to the large fusion-nuclei, with doubled 

 number of chromosomes, said by Nemec to be produced by 

 poisonous solutions acting on bean roots ; (4) that the influence 

 of poisons on mitosis is due to the great sensitiveness of the 

 achromatic structures, the spindle fibres being disorganised so 

 that the further progress of division is inhibited. The most 

 important conclusion arrived at by the author, however, is 

 that distilled water is itself a " toxic solution." If this be 

 confirmed, it must be inferred that various abnormalities of 

 cell behaviour which have been attributed to the effect of 

 toxic salts are not necessarily so produced, but may be due to 

 the osmotic action of the solution. It would appear, also, 

 that the practice of growing plants in distilled water — as 

 " controls " — in various physiological experiments is open to 

 serious objection, since such controls are themselves under 

 abnormal conditions, and show the same progressive decline 

 of cell function that occurs in " toxic " solutions, though at a 

 slower rate. 



GERMINATION OF RUST SPORES.— As is well known, 

 the spores of the Rust-Fungi (Uredincae) germinate in an 

 extremely irregular manner, and. until recently, no satisfactory 

 explanation of their apparently erratic behaviour in cultures 

 has been given. Schaffnit (Ann. Myc. 1909), from various 

 obse<-vations and experiments, concludes that the capacity of 

 Rust spores for germination depends largely on the degree of 

 maturity of the spores. The majority of the spores which are 

 shaken oft' by rain or by wind do not germinate ; and spores 

 which have been removed prematurely are incapable of ripen- 

 ing afterwards. Nor can spores ripen on leaves that have 



