OCTOBEK 28, 1921] 



SCIENCE 



415 



segments of the 14 chromosome group and 

 that no single unpaired chromosome would 

 be present in the reduction divisions. 



If the 14 and 21 chromosome species are the 

 result of reduplication we might expect a 

 considerable number of characters in the Em- 

 nier and Vulgare groups to be dependent on 

 multiple factors. Although many characters 

 of these groups are apparently dependent on 

 single factors there are a number of charac- 

 ters dependent on two or more factors. The 

 red color of grain may be determined by one, 

 two or three factors, and pubescence of chaff 

 and color of chaff have also been found to be 

 dependent on several factors in some eases. 

 A comparatively large number of multiple 

 factors affecting the same qualitative charac- 

 ters are reported in wheat. 



If the Vulgare group, the Emmer group, 

 and Einkorn differ only in chromosome com- 

 bination of 7X3, 7X2, and 7 X 1. why 

 should the different groups result in sterile 

 or partially sterile F^ plants and why should 

 the different groups vary so greatly in morpho- 

 logical characters ? Morgan has suggested 

 that for similar cases in other plants that 

 changes may occur in the individual chromo- 

 somes in the course of time so that the 

 original chromosomes would come to differ 

 in many factors. If the 14 and 21 chromo- 

 some species have originated by reduplication 

 of the 7 chromosome group such changes must 

 have occurred. The species within each group 

 overlap considerably, but each group is rela- 

 tively distinct in morphological characters. 

 BIarl Sax 



Maine Agricultukal Expeeiment Station, 

 May 6, 1921. 



ASTRONOMICAL MEETING AT THE 



POTSDAM ASTRONOMICAL 



OBSERVATORY 



The following is an abstract of a German 

 press report of the international astronomical 

 meeting held at Potsdam, August 24r-27 

 last. 



After a lapse of eight years the Astronomical 

 Society met again at Potsdam, under the presidency 

 of Professor Strbmgren of Copenhagen. Eepresent- 

 atives from sixteen nations were present. About 

 two hundred attended the meeting; from Scandi- 



navia, Professor Bohlin, Stockholm; Professor v. 

 Zeipel and Amanuens Asklofif, Upsala; Professor 

 Striimgren and assistant Miss VLiiter-Hansen, Co- 

 penhagen; from Christiania, observer Lous, and 

 from Finland Furuhjelm; from Holland Professor 

 Kapteyn as well as Van Rheja and Father Esch; 

 from England Professor Eddington, also Father 

 Cortie, S.J. ; among others were Professors Bausch- 

 inger, Hartwig, Einstein, Grossman, Nernst, Runge, 

 Schorr, Wiechert, Prey, and Kienle. 



Professor Stromgren in his address referred to 

 the continuance of the communication of astron- 

 omic phenomena during the years of stress through 

 the instrumentality of the Copenhagen observatory, 

 instead of from Kiel. Copenhagen served also as a 

 medium for the exchange of astronomic and scien- 

 tific literature. 



The scientific program contained many papers 

 showing the progress which astronomy has made of 

 recent years into details of which we can not here 

 enter. However, from Father Hagen we learn of 

 the immense masses of dark nebulae; from Kiihl 

 (Munich) explanation was given of many hitherto 

 unexplained astronomical phenomena shown in the 

 telescope as well as on the photographic plate ; from 

 Zeipel we learn of the determination of the masses 

 of the stars in the globular clusters and that they 

 obey the same laws as the molecules in a so-called 

 ideal gas. 



Rosenberg reported on the improvement of the 

 photo-electric method for the determination of 

 brightness of stars. The accuracy of measurements 

 approaches the 10,000th of a magnitude, v. Tamm 

 (Sweden) surprised the meeting with an ingenious 

 and simple method for the determination of the 

 color of stars photographically with a single ex- 

 posure. Professor Oppenheim (Vienna) presented 

 an interesting theory on the movement of the stars. 

 Dr. Moll of Utrecht spoke of a new micropho- 

 tometer for the measurement by means of a thermo- 

 pile of the distribution of brightness in stellar 

 spectra. 



A committee was appointed in connection with 

 an expedition for observing the solar eclipse next 

 year in the Dutch East Indies. It is intended to 

 repeat the experiment of Professor Eddington in 

 connection with the theory of relativity. 



A visit was paid to the observatories in Potsdam 

 and Neubabelsberg. They were shown also the 

 Einstein tower, a new structure to further test the 

 effect of relativity, the details of which were ex- 

 plained by Professor Freundlich. Professor Guth- 

 nick has been appointed director in succession to 

 would pair with entire chromosomes or larger 



