66 ILLINOIS ACADEMY OF SCIENCE 
equatorial belt when centrifugal separation is imminent. Oc- 
casional collisions are inevitable in the course of the krenal 
flights, and some of these flights are thereby converted into 
orbital flights. Thus the dominant types of molecular flights 
are: (1) within the atmosphere, intercollisional; (2) at the 
summit of the collisional atmosphere, krenal, (3) in the outer- 
most zone, orbital. The orbital atmosphere can only be formed 
from those molecules that have exceptional velocities, and 
hence its molecules carry exceptional energy and moment of 
momentum. The transfer of these exceptionally endowed 
molecules from the collisional atmosphere to the orbital atmos- 
phere makes relatively heavy drafts on the energy and moment 
of momentum of the rotating spheroid. The transfer is ac- 
celerated by every acceleration of rotation, and the draft of 
energy and moment of momentum is thus accelerated as the 
critical point of centrifugal separation is approached. This 
accelerated draft seems to be such that the equatorial velocity 
never quite reaches the stage at which separation en masse, or 
even partitively, can take place by simple centrifugal action, 
but only by this indirect mode. The molecules that pass thus 
individually into orbits have paths that vary much from one 
another and are scattered widely throughout the sphere of 
control of the spheroid. They do not form a simple ring close 
about the shrinking spheroid, as in the familiar Laplacian con- 
ception, nor do they follow closely the analogy of the small 
bodies that make up the Saturnian rings. They constitute a 
variety of planetesimals, with elliptical orbits promiscuously 
crossing one another, and subject to aggregation in much the 
same ways as the planetesimals of the spiral nebulae, save that 
there are here no nebulous knots to serve as collective nuclei. 
This last is a vital point, for, in the absence of collecting nuclei, 
the aggregates are likely to be many and small, rather than few 
and large as in our planetary system. The planetary family 
thus separated from a gaseous nebula in the course of its con- 
densation should consist of a multitude of small planetoids 
of eccentric orbits and rather diverse planes. A family of this 
type, on the near approach of a star at some later time, might 
be thrown into inextricable confusion and its members be liable 
to pass through the Roche limit of some other body of their 
own system, or of the new system, and to be torn into frag- 
ments which, as clustered groups, would be given very eccentric 
orbits. Such clustered groups of fragments are thought to 
