THE CONSTITUTION OF NEBULAE. 



33 



The interest aroused by these irregular and chaotic nebulous forms 

 is still further increased by the phenomena of the spiral or convoluted 

 nebula? with which the giant telescopes of Lord Kosse and Mr. Bond 

 have made us further acquainted. As a rule, there stream out from 



Fig. 5. 



Spiral Nebula in Canes Venatici. 



one or more centres of luminous matter innumerable curved nebulous 

 streaks, which recede from the centre in a spiral form, and finally lose 

 themselves in space. Fig. 4 represents a nebula in the form of a sickle 

 or comet-tail, and Fig. 5 shows the most remarkable of all the spiral 

 nebula?, situated in the constellation Canes Venatici. 



Fig. 6. 



Transition from the Spiral to the Annclar Form. 



It is hardly conceivable that a system of such a nebulous form 

 could exist without internal motion. The bright nucleus, as well as 

 the streaks curving round it in the same direction, seems to indicate 



