August 31, 1900.] 



SCIENCE. 



347 



uncertain figures can be recognized by tlie 

 type? 



3. Shall the International Atomic Weight 

 Commission have the current table of atomic 

 weights edited on this basis? 



In comment it may be mentioned that not all 

 teachers are troubled by using O = 16 as a 

 standard, and that there is a very large body 

 of chemists outside the ranks of teachers, to 

 whom this standard oflfers the decided advan- 

 tage, that with this a large share of the more 

 commonly used atomic weights approximate 

 very closely to whole numbers. J. L. H. 



In this plant also the chromatin is aggregated 

 into a central ball during the resting stage as 

 in some animal tissue. Those interested in the 

 details of the work may find a fuller account in 

 the Botanical Gazette for July of this year. 



K. M. WiEGAND. 



PLANT EMBBTO-SACS. 

 Some recent studies by the writer on the 

 young ovules of the lily-of-the-valley, pond- 

 weed (Potamogeton), and the garden canna 

 have shown a number of interesting features in 

 connection with the development of the embryo- 

 sac. The first division of the nucleus in the 

 hypodermal cell is heterotypic, while the next 

 two represent the ' reducing division '; hence in 

 these plants this cell strongly suggests the pol- 

 len-mother-cell of the anther. Apparent reduc- 

 tion takes place as usual just previous to the 

 heterotypic division. The reduced number of 

 chromosomes in the lily-of-the-valley was 

 eighteen, in pond-weed about eight, while in 

 canna it was only three, one of the smallest yet 

 recorded for plants. In the lily-of-the-valley 

 and pond-weed only the heterotypic division is 

 followed by a cell wall, thus resulting in an 

 ' axial row ' of two binucleated cells ; in canna 

 all three divisions produce transverse walls and 

 the axial row is therefore four celled. In the 

 first named plant both cells enter into the for- 

 mation of the embryo-sac, in pond-weed the 

 lower only, while in canna only the lowermost 

 of the row of four. Therefore in lily-of-the- 

 valley the embryo-sac contains all four nuclear 

 elements from the mother cell as in Lilium, in 

 pond-weed only two, and in canna only one. 

 Can the embryo-sacs in these cases be homolo- 

 gous structures, and should a macrospore con- 

 tain more than one of these nuclear elements ? 

 In pond-weed a membraneous pouch formed 

 around the egg-apparatus at a very early period 

 seems to preclude entirely the fusion of polar 

 nuclei to form the endosperm mother nucleus. 



SCIENTIFIC NOTES AND NEWS. 



The monument of Lavoisier, erected by in- 

 ternational subscription, was unveiled at Paris 

 on July 27th. There were present the members 

 of the fourth International Congress of Chem- 

 istry and a large number of scientific and pub- 

 lic men. M. Berthelot who was to have pre- 

 sided was unable to be present on account of 

 ill health, and his address was read by M. Dar- 

 boux. The monument was presented to the city 

 of Paris by M. Moissan, to whom M. Leygues, 

 the minister of public instruction, responded. 



Fairman Rogers, formerly professor of civil 

 engineering in the Universitj^ of Pennsylvania 

 and one of the original members of the Na- 

 tional Academy of Sciences, died in Vienna on 

 August 21st. He was born in Philadelphia in 

 1833, graduated from the University of Penn- 

 sylvania and was professor of civil engineering 

 in that institution from 1855 to 1870. From 

 1853 to 1865 he was also lecturer on mechanics 

 in the Franklin Institute. On retiring from 

 the professorship in the University of Pennsyl- 

 vania he became a trustee, and gave later to 

 the institution his valuable collection of works 

 on engineering. Mr. Rogers served as an en- 

 gineering ofiicer in the civil war and was con- 

 nected with the Coast and Geodetic Survey. He 

 was the anther of ' The Magnetism of Iron 

 Vessels ' and of numerous papers on scientific 

 and engineering topics. Mr. Rogers was for- 

 merly prominent in Philadelphia and New York 

 society, but has latterly lived abroad. 



The Paris ' Conference Scientia ' has given a 

 banquet to Lord Lister and will later entertain 

 in a similar manner Lord Kelvin. 



M. DuHEM has been elected a correspondent 

 of the Paris Academy for the section of me- 

 chanics. 



Dr. August Leppla has been appointed 

 State geologist and Dr. Oskar Zeise district 

 geologist in the Geological Institute at Berlin. 



