400 



NA TURE 



[Feuruary 4, 1909 



the fog was very dense, one's hair and overcoat also 

 received a Ihiclc deposit of hoar-frost. It is noteworthy 

 that in central London the fog, being exceedingly carbon- 

 aceous, and pungent with SO,, was too dry to deposit much 

 ice or rime on the trees in Hyde Park, although the grass 

 was thickly coated through terrestrial radiation. I have 

 never seen much hoar-frost on the bare forest trees without 

 fog, and I think that other observers will agree that the 

 presence of fog is necessary for any great thickness to 

 be formed. The dryness of the smoky town-fog as com- 

 pared with the country-fog is well known, and this 

 whether the temperature of the air is below the freezing 

 point, as in the case in question, or above it. On the 

 above dates at Northwood the fog dispersed for a couple 

 of hours at mid-day, and the sun shone upon a fairy- 

 land in a sky of cloudless blue. 



L. C. W. BONACINA. 



Northwood, Middlesex, Februarv i. 



Germination of the Broad Bean Seed. 



The text-book statements on the relation of the micro- 

 pyle to the radicle are entirely wrong so far as I have been 

 able to observe. If the testa be carefully removed it will 

 be found to have two compartments, the larger one cover- 

 ing the cotyledons and the smaller sheathing the radicle. 

 A fine bristle passed through the micropyle enters the 

 cotyledon compartment. When the radicle emerges it does 

 not pass through the micropyle, which is left intact, but 

 the testa splits along two lines of weakness running from 

 the tip of the radicle to its junction with the cotyledon 

 stalks. 



I noticed this about six years ago, and though I attach 

 no importance to the mere fact, its interest is considerable 

 from the point of view of nature-study in schools. 



E. Heber Smith. 



Episcopal Training College for Teachers, Dairy House, 

 Orwell Place, Edinburgh, January 19. 



"Vestiges of the Natural History of Creation." 



In " Vestiges of Creation," ninth edition, 1851, p. ii_i, 

 it is stated that two independent investigators caused the 

 production of " living insects " (Acartis crossii) by the 

 prolonged action of a voltaic battery upon certain chemical 

 solutions. The description is most matter-of-fact. The 

 second experimenter seems to have sterilised his apparatus 

 and solutions before use ; yet it is said that the insects 

 " were sometimes observed to go back to the fluid to feed, 

 .Tnd occasionally they devoured each other." In Note 54 

 it is also stated that " after they have escaped from the 

 solution they live in the neighbourhood, and readily breed." 



I shall be much obliged if any reader can explain the 

 above phenomenon, or say if the experiments have been 

 repeated. F. Wyville Thomson. 



Caledonian United Service Club, Edinburgh, 

 January 28. 



THE RADIVM INSllTUrE. 

 'X' HE announcement that, on the initiative of the 

 * King, a Radium Institute will shortly be opened 

 in London is of the greatest interest to the man of 

 science and to the physician. The institute is intended 

 not only for research work, but also for curative pur- 

 poses, and it will have an organised medical depart- 

 ment. The whole of the funds necessary to build, 

 equip, and maintain a new establishment are being 

 provided by Sir Ernest Cassel and Lord Iveagh. We 

 are reminded that Lord Iveagh gave the munificent 

 sum of 250,000/. to endow the Lister Institute of 

 Preventive Medicine, so that his name will now be 

 associated gratefully with two great endowments of 

 science. The committee of the institute will consist of 

 .Sir Frederick Treves, Bart., G.C.V.O., C.B. (chair- 

 man). Sir William Ram.sav, K.C.B., F.R.S., Sir J. J. 

 Thomson, F.R.S., the Hon. R. J. Strutt, F.R.S., 

 Sir Lauder Brunton, Bart., F.R.S., Sir Malcolm 

 NO. 2049, VOL. 79] 



Morris, K.C.V.O., and two other members, one each 

 to be nominated by Sir Ernest Cassel and Lord 

 Iveagh. 



The interest which the King is exhibiting in the 

 inauguration of a scientific institution for further 

 research work with radium, so that its powers may be 

 utilised for the amelioration of human suffering, has 

 led to the publication in the Press of the useful pur- 

 poses to which radium may be put, and the inaugura- 

 tion of the Radium Institute will provide another 

 example of the supreme importance to mankind of 

 research work in science. The difficulty hitherto has 

 been that so little of this remarkable body has been 

 available for research. The trouble has been a 

 financial one. Not long ago good specimens of radium 

 bromide were obtainable for 5L per milligramme, but 

 recently the price has reached 16/. to 18/. per milli- 

 gramme. It is obvious that in any case an enormous 

 expenditure is required before a sufficiency can be 

 obtained adequate for an institute, for the investigation 

 of the properties of radium and its application for the 

 treatment of disease. The necessary funds having 

 now been provided, it will be possible to studv radium 

 from many points of view. 



Radium is the most interesting of a group of bodies 

 characterised by the property of spontaneously emitting 

 radiations capable of passing through plates of metal 

 or other substances impermeable to light. In i8g6, 

 Becquerel found that uranium compounds and the 

 metal itself give off rays which cause changes in a 

 photographic plate even when passed through thin 

 plates of metal. Uranium was isolated from pitch- 

 blende so long ago as 1789 by Klapworlh, and a little 

 more than a hundred years later, in 1898, M. and 

 Mme. Curie discovered that certain varieties of this 

 mineral possess greater radioactivity than could be 

 accounted for by the uranium they contained. Thev 

 were led to investigate these forms of pitchblende, and 

 succeeded in isolating two new elements, polonium rmd 

 radium. 



The discovery of radium and its investigation have 

 opened up enormous fields of research, and the follow- 

 ing brief account of what has been done will suggest 

 the possibilities before the Radium Institute, especiallv 

 if a considerable quantit}' of the element can be under 

 investigation. 



Radium gives off three kinds of rays, respectively 

 called a, /3, 7 rays, which have various properties. The 

 o rays are identical with the radiations of higli 

 velocity, carrying a positive charge of electricity, whicli 

 are projected through a perforation in the kathode of 

 a Crookes's tube. They have been called " canal 

 rays " by Goldstein, and have been investigated par- 

 ticularly by Wien. They travel in the opposite direc- 

 tion to the current through the tube, and have the 

 power of ionising gases. The 8 rays consist of nega- 

 tive particles, identical with the rays which are given 

 off from the kathode and called " kathode rays." They 

 have a velocity equal to that of light, and can be 

 deviated by a magnetic field. The y rays are similar 

 to the X-ravs. They are not deflected by a magnetic 

 field. 



These rays have different powers of penetration. 

 This is estimated by interposing layers of aluminium. 

 The a rays have the least penetrative power; according 

 to Rutherford, they may be taken as unity, the /3 rays 

 as of a penetrative power of 100, and the 7 rays as 

 of a penetrative power of 10,000. Practically the rays 

 may be filtered by interposing layers of aluminium 

 and lead. For instance, both the a and /3 rays are 

 completely absorbed by a layer of lead only one centi- 

 metre thick, but the 7 ravs will pass through a laver 

 of lead an inch thick. Thev are more penetrating 

 than the X-ravs. 



