43^ 



NA rURE 



[March 12, k 



Disease-resisting Sugar-canes. 



It is observed in your issue for November 7 last in 

 tile article entitled " Immunity to Disease among Plants," 

 being an abstract of a letter delivered before the British 

 Pharmaceutical Conference at Manchester by Prof. F. E. 

 Weiss, that the following statement occurs : — 



" In the West Indies, the Bourbon cane has been given 

 up on account of disease, but very useful and disease- 

 resisting hybrids have been produced by crossing the 

 valuable but easily attacked Tjeribon cane with the 

 resistant Indian Tschan cane." 



The latter canes are not known in the West Indies, and 

 it is desirable, therefore, that the actual facts be placed 

 on record. 



When the Bourbon sugar-cane had to be abandoned in 

 the West Indies on account of its susceptibility to fungus 

 disease, its place was generally taken by the White Trans- 

 parent — an introduced variety. Since then the latter is 

 being largely replaced by seedling canes. These seedlings 

 have been produced in some instances from the Bourbon 

 cane, and, recently, almost entirely 

 from the better of the newer seedling '•vr^o^ 



varieties under experiment. It may be 

 of interest to mention that in British 

 Guiana the area under cultivation with 

 varieties of sugar-cane other than 

 Bourbon is about 30,000 acres, and the 

 greater portion of this area is occupied 

 by seedling canes. In the island of St. 

 Kitts about 71 per cent, of the sugar- 

 cane acreage is occupied by seedlings. 

 Seedling canes are also being largely 

 planted at Barbados, Antigua, St. 

 Lucia, and Jamaica. Many of the 

 newer seedlings appear to be immune 

 to some of the fungus diseases that 

 affect the sugar-cane in these colonies, 

 and the efforts in the direction of pro- 

 ducing seedling canes by artificial 

 cross-poliination give promise of 

 success. 



In Java the circumstances are also 

 somewhat similar. The Cheribon cane 

 had to be abandoned on account of its 

 being liable to the " sereh " disease, 

 and amongst the foreign varieties intro- 

 duced to take its place was the East Indian cane 

 Chunnee. In 1894 it was found that the Cheribon 

 cane bore a large proportion of infertile pollen with a 

 normal ovary, while the Chunnee produced a very large 

 quantity of fertile pollen. Advantage was taken of this 

 to plant the two varieties side by side in the hope of 

 producing hybrids by natural means. Considerable success 

 has been attained, for a very large number of seedlings 

 was obtained by sowing seeds from the " self-sterile " 

 arrows of the Cheribon, many of which combine the high 

 sugar content of the Cheribon with the disease-resisting 

 power of the Chunnee. Other introduced canes have also 

 been used in these experiments, and somewhat similar 

 experiments are in progress in the West Indies. 



A riisumi of the " Improvement of the Sugar-cane by 

 Selection and Hybridisation " (with coloured plates) was 

 presented by Mr. F. A. Stockdale and myself at the con- 

 ference on genetics held in London in .August, 1906, under 

 the auspices of the Royal Horticultural Society. The 

 society issued a full report of the conference in February, 

 1907. The paper referred to has since been reproduced in 

 the West Indian Bulletin (vol. vii.. No. 4). 

 Barbados, February 14. D. Morris. 



Modern Views of Electricity. 



To avoid misunderstanding, I write to say briefly, in 

 connection with a review by " N. R. C." on p. viii of 

 the supplement to Nature of March 5, that I have never 

 supposed space to be a conductor, but have always taught 

 the opposite view ; and that I have never imagined 

 unmodified ether to be subject to gravitation, or to be 

 other than the vehicle of that property of matter. If any 

 phrases in my book suggest the contrary they are examoles 

 of faulty expression. But I would add, parenthetically, 

 that I should not scruple to speak, untechnicallv, of the 

 centre of gravity of a surface. Oliver Lodge. 



NO. 2002, VOL. y/l 



Rothesay Summers and Greenwich Winters. 



Last summer at Rothesay (N.B.) was very wet, with 

 14-8 inches (average, 11-3 inches). The current winter 

 season at Greenwich may now be pronounced a mild one. 



It is a curious fact (whatever the e.xpl.anation) that a 

 very wet summer at Rothesay tends to be followed by a 

 mild winter at Greenwich, and a very dry summer bv a 

 severe winter. This is connected, I believe, with the fact 

 that the rainfall of Scotland and the winter cold of Green- 

 wich both exhibit pretty clearly the influence of the sun- 

 spot cycle. 



Suppose we pick out the twenty-two wettest and the 

 twenty-two driest summers at Rothesay in the sixty-six 

 years 1841-1906 (i.e. a third in either case). The former 

 group range from 19-1 inches down to 12-6 inches; the 

 latter from 5-9 inches up to 107 inches. Next, consider 

 what sort of winter at Greenwich followed each of these 

 (say, how many frost days in the period September to 

 May). 

 These winters may be represented as in diagrams A and 



5^ 



JV 



The scale of frost days 

 at top of each diagra 

 summers. 



nd that of the 

 rs. li, Winter; 



its position both the number 

 and its position in the sun- 



B, where a dot indicates by 

 of frost days of one winter 

 spot cycle. 



It will be seen that the twenty-two " very wet " 

 Rothesay summers were followed by fifteen mild and seven 

 severe winters at Greenwich (A), and the twenty-two 

 " very dry " Rothesay summers by fifteen severe and seven 

 mild winters at Greenwich (B). The contrast is still more 

 pronounced if we confine attention to the period of decline 

 of the sun-spots. 



These diagrams seem to warrant two practical rules, 

 which may be thus stated : — 



During decline of the sun-spots, if summer rainfall at 

 Rothesay exceeds 126 inches, a mild winter at Greenwich 

 is highly probable (say, 6 to 1), and if during the same 

 period the Rothesay summer rainfall is under 107 inches 

 a severe winter is highly probable (say, 3 to i). In the 

 former case a very severe winter, and in the latter a very 

 mild winter, would seem to be excluded. 



We are at present close to a maximum (1905 or 1907?), 

 and have to do with diagram A, which shows no severe 

 winters for the corresponding position in the cycle. 



.^LEX. B. MacDowall. 



The Possibility of Life in Mars. 



.At the risk of behig thought by your correspondent, Mr. 

 C. O. Bartrum, an " anthropomorphist," I consider that 

 Prof. Lowell in his admirable investigations of the mark- 

 ings of Mars is quite reasonable in ascribing the change 

 of colour to the presence of a vegetation containing a sub- 

 stance allied to, if not identical with, chlorophyll. I do 

 so because the spectroscope has shown that, not only the 

 solar system, but the whole universe, is built up of 

 inorganic elements similar to those found on the earth. If 

 we find unity of plan pervading the structure of the most 



