September 13, 1901.] 



SCIENCE. 



407 



the eggs of Triton in the two-celled stage, 

 his method permitting of different degrees 

 of conBtriction and of constriction in differ- 

 ent planes, as well as a thorough study of 

 the resulting abnormalities ; and by E. B. 

 Wilson, who gave the results of his studies 

 on the cytological changes in t^e eggs of 

 Toxopneustes developing parthenogenetically 

 by the Loeb method. 



In the section for systematic zoology of 

 the vertebrates one of the most interesting 

 exhibits was that by Sclater of the skull 

 and a portion of the skin of the newly dis- 

 covered Okapia, a giraffine animal closely 

 related to the extinct Helladotherium and ob- 

 tained in the Urganda district by Sir Harry 

 Johristoii. The papers and demonstrations 

 in the section for invertebrata were numer- 

 ous, and it is impossible to refer to more than 

 a few of them. Most noteworthy was per- 

 haps a magnificent collection of Hexactinel- 

 lid sponges obtained from the Japanese seas 

 and exhibited by Professor Iijima,of Tokyo, 

 while other papers of interest were by Mc- 

 Bride on the development of Echinus escu- 

 lentus, Apathy on the visual cells of the 

 Herudinea (both these with demonstra- 

 tions), Hoyle on intrapallial luminous or- 

 gans in the Cephalopoda and Simroth on 

 the digestive canal of the MoUusca. The 

 section on nomenclature devoted a consid- 

 erable portion of its time to a consideration 

 of the report of the commission proposed at 

 the last Congress and appointed a commit- 

 tee to codify the rules as they now exist. 



The arrangements for the meeting were 

 admirably carried out. Through the cour- 

 tesy of the president of the Reichstag the 

 sessions of the Congress were held in the 

 Eeichstag building and everything was 

 done to make the meeting enjoyable in 

 every way. The death of the Empress 

 Frederick naturally cast a gloom over the 

 city and entailed considerable alterations 

 in the program of excursions and festivi- 

 ties which had been planned by the com- 



mittee, but withal they were fully suc- 

 cessful in their efforts to make the meeting 

 both intellectually and sociallj' enjoyable 

 for all those in attendance. 



The next Congress will be held in Berne, 

 Switzerland, in 1904, and Professor Studer, 

 of Basel, was unanimously chosen as presi- 

 dent-elect. 



J. P. McM. 



SCIENTIFIC BOOKS. 

 Annals of the Astrophysical Observatory of the 



Smithsonian Institution. Vol. I. By S. P. 



Langley, Director, aided by C. G. Abbot. 



Washington, Government Printing Office. 



During the ten years of its existence the 

 Smithsonian Astrophysical Observatory has 

 been almost entirely devoted to the prosecu- 

 tion of a single research — a continuation of one 

 begun some years ago by Professor Langley at 

 Allegheny — namely, the production of a map 

 of the absorption lines in the infra-red solar 

 spectrum which would be in some measure 

 comparable as regards completeness and pre- 

 cision with those of the visible region produced 

 photographically with the aid of the grating. 

 Besides this main research — and carried out 

 largely since its completion — several subsidiary 

 researches have been undertaken, one of 

 which, to be mentioned later, is of particular 

 importance. 



If we represent the solar radiation by an 

 energy curve, in the usual manner, in which 

 ordinates are proportional to radiant energy, 

 and abscissae to wave-lengths, the selective 

 absorption of the solar and terrestrial atmos- 

 pheres will be indicated by depressions in the 

 curve, whose depth and width will show the 

 intensity of the absorption and the extent of 

 the spectral region affected by it. In the 

 visible region, of course, the absorption will 

 be indicated by a great number of more or less 

 sharp, close-packed depressions, corresponding 

 to the great number of visible ' lines.' It has 

 been found that, besides broad regions of gen- 

 eral absorption previously noted by Langley 

 and others, the infra-red spectrum is also af- 

 fected by similarly sharp selective absorption, 

 producing 'lines,' and as has been said, this 

 main research is devoted to the mapping of 



