C 34 ) 



of mammals even with a very strong precipi tin-serum, which was 

 obtained with and against an arbitrary mammifer-albumen ("mamma- 

 lian reaction"). Hauser ^) comes to a similar result; only quantitative 

 differences remain. 



Also with relation to the amboceptor such a diminution of the 

 specific action seems to me sufficiently well pointed out. 



Physics. — ''Arbitrary distribution of light in dispersion bands, and 

 its bearing on spectroscopy and astrophysics." By Prof. W. H. 

 Julius. • 



In experimental spectroscopy as well as in the application of its 

 results to astrophysical problems, it is customary to draw conclu- 

 sions from the appearance and behaviour of spectral lines, as to the 

 temperature, density and motion of gases in or near the source of 

 light. 



These conclusions must in many cases be entirely wrong, if the 

 origin of the dark lines is exclusively sought in absorption and that 

 of the bright ones exclusively in selective emission, without taking 

 into account the fact that the distribution of light in the spectrum 

 is also dependent on the anomalous dispersion of the rays in the 

 absorbing medium. 



It is not in exceptional cases only that this influence makes itself 

 felt. Of the vapours of many metals it is already known that they 

 bring about anomalous dispersion with those kinds of light that 

 belong to the neighbourhood of several of their absorption lines "). In 

 all these cases the appearance of the absorption lines must to a greater 

 or less extent be modified by the above mentioned influence, since the 

 mass of vapour, traversed by the light, is never quite homogeneous. 



Hence it is necessary, separately to investigate the effect of dis- 

 persion on spectral lines; we must try to separate it entirely from 

 the phenomena of pure emission and absorption. 



A first attempt in this direction were the formerly described 

 experiments with a long sodium flame '), in which a beam of white 



1) Munch. Med. Wochenschrift, 1904, n" 7, S. 289. 



2) After Wood, Lummer and Pringsheim, Ebert, especially Pucgianti has inves- 

 tigated the anomalous dispersion of various metallic vapours. In Nuovo Cimento. 

 Serie V,' Vol. IX, p. 303 (1905) Pugcianti describes over a hundred hnes, showing 

 the phenomenon. 



^) VV. H. Julius, "Dispersion bands in absorption spectra." Proc. Roy. Acad. 

 Amsl. VII, p. 134-140 (1904). 



