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NATURE 



[August 21, 191 



of the mutants at least, a fundamental change in the 

 structure of the nuclei had taken place, and that the 

 external changes of characters in mutation had their 

 origin in internal structural changes of the cells and 

 their nuclei. 



The premutation hypothesis, formulated by de Vries 

 to account for the origin of the mutations before the 

 facts regarding their cell-structure were known, 

 assumes that new units gradually accumulated in the 

 germ plasm of the species previous to the beginning 

 of the mutation process, and that these afterwards 

 passed from a latent to an active condition, thus pro- 

 ducing the mutations. But since the structure of the 

 nuclei in these forms is now known, and the manner 

 in which changes in that structure originate, this 

 hypothesis has been superseded, and the conception of 

 a mutation period is no longer needed. 



Various writers have also suggested that the muta- 

 tions of CEnothera were merely re-combinations of 

 characters, such as occur in Mendelian hybrids. This 

 hypothesis is also contrary to our present knowledge 

 of the nuclear structure and behaviour in CEnothera, 

 and furnishes another instance, like that of the sex- 

 chromosomes, where nuclear studies throw light upon 

 the nature of the processes of heredity and variation. 

 By combining the study of nuclear and cell structure 

 with that of external characters, it is evident that 

 much further insight into the nature of mutation and 

 heredity may be gained. 



A specific case of the type of germinal change here 

 referred to is that of Oenothera lata. It has recently 

 been found that when combined with characters de- 

 rived by inheritance from various other forms (e.g. 

 O. biennis, grandiflora and rubricalyx), the char- 

 acteristic foliage and habit of lata is always accom- 

 panied by the presence of an extra chromosome in 

 the nuclei of the plant, making the number of 

 chromosomes fifteen instead of fourteen. In other 

 words, this type of foliage is constantly associated 

 with the presence of an extra chromosome. 



Mutations are by no means confined to the evening 

 primroses, but are now known, through experimental 

 studies, to occur in bacteria, fungi, mosses, and many 

 flowering plants. And among animals, instances of 

 sudden and inherited departure from the parent form 

 occur in various groups from Protozoa to man him- 

 self. 



The new characters thus appearing form a varied 

 and motley array, differing often in most unexpected 

 vyays from their parent types. Many of these muta- 

 tions appear "spontaneously," that is, from unknown 

 causes. _ These are probably often an indirect result 

 of previous crossing-, change of climate, &c. Others 

 have been directly produced by a variety of experi- 

 mental conditions. The study of the causes of these 

 germinal aberrations and the manner of their produc- 

 tion is evidently destined to play an important role 

 in future experimental evolution. The results already 

 achieved point to a wide and important field of re- 

 search in the application of these methods to horti- 

 culture, agriculture, and experimental breeding-. 



R. Rugcles Gates. 



OBSERVATIONS IN THE SOUTH MAG- 

 NETIC POLE AREA. 

 T BEG herewith (o enclose what I trust will prove 

 for the scientific world in general an important 

 preliminary report by Mr. E. X. Webb, magnetician 

 to Dr. Mawson's Australasian Antarctic Expedition, 

 on the magnetic work, and particularly the absolute 

 readings taken by Mr. Webb himself on a very fine 

 journey made by him and Mr. J. F. Hurley, under 

 -hip of Lieut. Page, in the direction of the 

 XO. 2286, VOL. qi] 



south magnetic pole for the distance of 300 miles to 

 the south-east of Dr. Mawson's base at Common- 

 wealth Bay in Adelie Land. 



You will see that a large number of very valuable 

 observations have been obtained on the north-west 

 side of the south magnetic pole area, and these, when 

 considered with the observations — fewer in number 

 but accurate — taken by Dr. Mawson himself on the 

 occasion of the Shackleton expedition on our approach 

 on the south-east to the south magnetic pole area, 

 should now enable the position of the south magnetic 

 pole in 1912 to be calculated with a degree of accuracy 

 considerably in advance of anything previously 

 attained. 



I have ventured to add some notes in reference to 

 the observations made by Dr. Mawson in the party — 

 consisting of Dr. Mawson, Dr. A. T. McKay, and 

 myself — of which I was leader in a journey to the 

 south magnetic pole area in 1908-9. I send with it 

 a plan on tracing cloth showing the route followed 

 by the Australasian Antarctic Expedition, with the 

 positions of the stations where Webb made his ob- 

 servations. T. W. Edgeworth David. 



University of Sydney, May 26. 



Mawson's Australasian Antarctic Expedition. 



Preliminary Report on Magnetic Work, by E. N. 



]\'ebb, Magnetician. 



Early in December of 191 1 the Australasian Ant- 

 arctic Expedition, under the leadership of Dr. Maw- 

 son, left Australia to carry out a programme of scien- 

 tific investigation on the Antarctic continent. 



It was intended to conduct a magnetic observatory 

 at one base station, and to make a magnetic survey of 

 the coast between Cape Adare and Gaussberg. A 

 large portion of this plan was successfully carried out. 

 Through the kindness of Dr. Bauer, director of the 

 department of terrestrial magnetism of the Carnegie 

 Institution of Washington, D.C., the writer was 

 trained during five months' field survey work in Aus- 

 tralia, under Mr. E. Kidson, one of the department's 

 observers. 



Absolute instruments were lent by the Carnegie In- 

 stitution, consisting of two unifilar magnetometers, 

 one Kew pattern and one Lloyd-Creak dip circle, by 

 Dover, Charlton, Kent, both fitted with 6 in. declino- 

 meter needles, and total intensity attachments. 



Intercomparisons of all instruments with a set used 

 by Mr. Kidson were made at Hobart before going 

 south ; also, the Eschenhagen magnetographs, com- 

 prising declination, horizontal and vertical intensity 

 variometers, were set up under the direction of Dr. 

 J. M. Baldwin, first assistant at Melbourne Observa- 

 tory. Both the observatory and the field work at the 

 main base were in charge of the writer. Field survey 

 work was commenced at Macquarie Island, where 

 determinations of the magnetic elements were made 

 at two stations, one at the extreme north of the 

 island, and the other at Caroline Cove. The average 

 of determinations at the north end gave declination 

 18 25' E. ; horizontal intensity, 0-13990; dip, 

 77 47S' S. Leaving Macquarie Island, the expedition 

 proceeded to Adelie Land, and at Commonwealth Bay 

 in latitude 67 00' S., longitude 142 39' E., landed 

 the main party. Here two magnetic huts were erected. 

 In the larger, which was carefully constructed to 

 resist wind and change of temperature, the magneto- 

 graphs were set no with the frames on solid rock, 

 and nut in working order on March 21, K112. Tem- 

 perature-compensating systems were fitted to the H. 

 and Z. variometers, and temperature effects have been 

 almost entirelv eliminated. Deflections were made 

 once a fortnight for scale values. 



