1000 



SCIENCE, 



[N. S. Vol. V. No. 130. 



paper on the atomic weight of tungsten, which 

 will appear in the Transactions of the Academy. 

 The tungstic trioxide was prepared from so- 

 dium tungstate and gave no traces of silica, 

 niobio or tantalic oxides, iron or manganese, the 

 alkalies or alkaline earths, or molybdenum. The 

 acid was transformed to ammonium salts. By 

 fractionating these, the following atomic weights 

 were obtained, quantities of from 1.5 to 5 

 grams being used. The different series had 

 been subjected to a different, previous prepara- 

 tion. 



Seeies a. 



1st Fraction 182.34 



2d " 182.77 



3d " 179.92 



4th " 183.45 



5th 

 5a 



Seeies B. 

 182.34 

 174.63 

 181.87 

 181.79 

 174.87 

 177.87 

 176.79 



Another portion of the trioxide, fractionated 

 by a diflferent method, gave on successive re- 

 ductions and oxidations of the same portion the 

 following series, in which it will be noted that 

 the weights increase with the oxidations and 

 diminish with the reductions : 



Reduction. Oxidation. 



At. Wt. 182.68 184.65 



177.25 185.26 



174.00 191.61 



The results of fifty determinations gave at- 

 omic weights ranging between 154.064 and 

 191.61. A series of experiments, that were 

 only briefly referred to, established the fact 

 that in all preparations of WO3 nitrogen was 

 present, even after repeated reduction. Miss 

 Hitchcock was led to conclude that as regards 

 volatility, metallic tungsten is more volatile 

 than the oxide. Wolframite was found to con- 

 tain both hydrogen and nitrogen, and scheelite 

 has large quantities of nitrogen. 



J. F. Kemp, 

 Secretary. 



ZOOLOGICAL CLUB, UNIVERSITY OP CHICAGO, 



MEETING MAY 19. — ABSTRACTS OP PAPERS 



PRESENTED. — ORIGIN OF THE PRONEPHEIC 



DUCT IN SELACHIANS. 



There have been difierent opinions as to the 

 origin of the Pronephric Duct in Selachians. 

 Acanthias embryos were used in making a re- 



newed study of the subject. The Anlage of 

 the Pronephros consists of segmental out- 

 growths of the somatic layer of the somites 

 from the seventh to the twelfth segments. 

 These are connected with the ectoderm at theii* 

 outer edge. This fusion early disappears. The 

 tip of the distally growing duct was constantly 

 fused with the ectoderm. One case of Karyo- 

 kinesis between ectoderm and duct was found. 

 Growth also takes place throughout the length 

 of the duct. Frontal sections showed six 

 Pronephric tubules on the right side with 

 aortic diverticula between. Connected with 

 the aorta there were also found structures 

 which may be interpreted as glomi. 



From the facts here given we conclude that 

 the earliest Anlage of the Pronephros fuses 

 temporarily with the ectoderm and may pos- 

 sibly receive some few cells from it. The first 

 part of the duct proper seems to share to some 

 slight degree in the mesodermal origin of the 

 anterior region. So far as the duct develops 

 distally the connection of its tip with the ecto- 

 derm is maintained. This fusion would be suf- 

 ficient evidence of a genetic relation for those 

 who accept the principle of the teloblastic 

 growth of organs. On the appearance of the 

 paper by Rabl the preparations were again ex- 

 amined carefully, but without finding any 

 grounds for abandoning the view that there is 

 a genetic connection between the duct and the 

 ectoderm in Selachians. 



Emily Eay Gregory. 



Dr. Whitman followed with a paper on ' The 

 Development of the Wing-bars in Pigeons. ' 



NEW BOOKS. 



Catalogus Mammalium tarn viventium quam fos- 

 silium. E. L. Teouessart. Fasciculus II. Car- 

 nivora, Pinnepedia Rodentia 1. Berlin, K. 

 Friedlander & Sohn. 1897. Pp. 219-452. M. 10. 



On the Origin of the European Fauna. E. F. 

 SCHARFP. Dublin University Press. 1897. 

 Pp. 427-514. 



Some Observations of a Foster Parent. John 

 Charles Taevee. Westminster, Archibald 

 Constable & Co., 1897; New York, The Mac- 

 millan Co., 1897. Pp. x + 282. $1.75. 



Electro-metallurgie. Ad Minet. Paris, Gau- 

 thier-Villars et flls. 1897. Pp. 195. 



