20 BOHLIN, ON THE GALACTIC SYSTEM WITH REGARD TO IST STRUCTURE. 
surrounded by fainter nebulosity of atmospheric appearance. This is the case of 
the Closed nebule. Some of these objects are referred to as »blue nebule» other 
as »pale nebul2>. 
2. The Galactic System is supposed to have been such a planetary nebula, 
which in the manner above described has broken down at its poles, being at present 
at a pretty advanced stage of a Ring Nebula. The centre of the System is poin- 
ted out by a Nucleus consisting of the assemblage of the Globwlar Clisters. The 
Spiral Nebule around its poles are to be considered as the products of the broken 
parts of the shell, while the Milky Way again is derived from its equatorial belt. 
Therein exist at present certain tirregular gaseous nebule of great extent, due to 
latter collisions and frictions, by which the original state of matter, once characte- 
ristic of the ring nebula, have been revived. 
3. The Planetary Nebule are considered as the individuals of a stratum — as 
it were a shoal of worlds — of even considerable breadth and thickness. 
Fig. 4. Stratum of Planetary Nebulce. 
e or e ee 9 + 8 LJ ö ec 
9 e LJ e 
e . e i Å e e é 
8 LÅ e ? e Oo e 3 , - 
e e Direction to 
Ö eo 
é Ge + es 5 > . Cygnus 
ET u SN OR 
By placing the Galaxy at G near the head of the stratum and somewhat to 
the side, one accounts easily for the particulars of spherical distribution of these 
objects; especially for the abundance of bright planetary nebulx& and stellar nebulz in 
the regions about Cygnus, and for a still existing sligth tendency to concentration of 
these nebul&e in respect to the Milky Way. 
