Proceedings Am. Philos Soc. Vol. XLIX No. 195 



Plate XXXI. 



Spiral Nebulae Photographed at Lick Observatory by Keeler and Perrine 

 (Publications Lick Observatory, vol. VIII). 



M. 51 Canum Venaticorum ; M. loi Ursae Majoris; 



H. IV 13, Cvgni ; H. IV 76. Cephei : 



H. I 53, Pegasi: H. I 55, Pegasi. 



These photographs show that the attendant bodies are not thrown off by 

 rotation, but begin forming in the distance and are gathered in towards the center 

 as the whirlpool settles under its own gravitation. 



