( J26 ) 



peculiarity of the distribution of the different kinds of nebulae may 

 then be considered as a natural sequence of the same cause as 

 in the agglomerations of the Galaxy has given rise to a type of stars 

 differing in constitution and distribution from those outside the 

 Milky Way. 



For the investigation of the problem mentioned at the head of 

 this paper we must take into consideration : 



a. The place of the sun in the solar system. 



b. The great (litïiculty to detect a nebula as compared with a star 

 at the same distance from us which has the same quantity of matter. 



Further T adopt as eslablished : 



1. Tiuit besides a gradual increase in the number of stars towards 

 the galactic plane there exist real agglomerations in the galactic region. 



2. That tlio sun is situated in a region of the Milky Way which 

 is relatively poor in sturs, hence as to the type of distribution in a 

 region that must be considered as "extra-galactic", or perhaps in a 

 transition layer. (Comp. Kaptp:yn, Ver.^1. K. A. r. IF. 1892/93, /^//7//. 

 Groningen, n° 11, p. 32 ; Easton, Astr. Nachr. 3270, Seeligek, Betracht. 

 p. 627; Newcomb, The Stars, Chap. XX). 



As pi'obable : 



3. That the system of stars is contained within a spheroid with 

 the galactic plane as its principal plane (Seeligek). 



And from my own investigations {Versl. K. A. v. W. 1897/98; 

 Astro i)hys. Journal XII, 2; Verhand. K. A. v. W. VIII, 3) it seems 

 to follow : 



4. That in the Cygnus-Aquila region of the Milky Way the 

 preceding branch is much nearer to us than the following. 



5. That the brightest galactic portion in Cygnus occupies almost 

 a central position in the system of the stars. 



Now, while discussing the distribution of the nebulae catalogued after 

 visual observation, I shall try to give an explanation founded on 

 the supposition that, the dim light of the nebulae in general taken 

 into consideration, the very distant nebulae escape visual observa- 

 tion (though they for tlie greater part perhaps may be registered photo- 

 graphically), and hence that, according to a\ hat has been said above 

 especial 1}^ sub 4, the very distant part of the system in which the 

 Aquila branch of the Galaxy is situated, must be disregarded. 



If the sun lies about in the central plane of the system in a poor 

 region amidst galactic agglomerations, and if that poor region is 

 comparable with the "extra-galactic" regions on either side of the 

 galactic plane, the thus connected "extra-galactic" regions acquire more 



