ADDRESSES 69 
spirals, the penetrations of the Roche limit, the grazing ap- 
proaches, and the glancing collisions, the still more effective 
members of the spiraloid series, while the center-to-center col- 
lisions form the extreme climax of the series, giving rise to 
irregular and radiant dispersions attended by extreme disso- 
ciation. The center-to-center collisions obviously destroy a 
large part of the motion of translation of the colliding stars by 
converting the energy of translatory motion into energy of 
dispersion. If, as suggested, the attendant dissociation de- 
velops the primoidal spectral state appropriate to a new stellar 
cycle, the coincidence is suggestively happy. 
The evolution of suns is of a higher order than the evolution 
of planetary systems. The evolution of organized star clusters 
and stellar galaxies is of a still higher order. In these, suns are 
but the units. In the dynamic organization of star clusters and 
galaxies there is a return to the orbital realm. And here again, 
the fundamental agency may prove to be the Janus-faced 
function of gravity acting paradoxically and partitively as 
a dispersive as well as centralizing agency. It has already 
been mentioned in passing that galaxies swinging near one 
another, or interpenetrating one another eccentrically, may 
develop spiraloid configurations on principles closely like those 
assigned to the origin of spiral nebule, If this view is justified, 
or so far as it is justified, our planetary hypothesis finds a cor- 
relative in an undeveloped gallactic hypothesis. 
It will perhaps be generally conceded that the energies that 
express themselves in orbital activities transcend those that 
express themselves in gaseous activities. In like measure, 
orbital cosmogony seems to transcend gaseous cosmogony in 
dynamical potency. But there are interchanges between them 
and no doubt an equilibrium between them. That both have 
fields whose immensity and intricacy transcend all human 
grasp goes without the saying. 
