A comparison of the Galactic System with other stellar systems might be based on:

1. (a) the regular aspect (the population 11);

2. (b) what we might call the semi-chaotic aspect, presented by the gas and the other population 1 objects;

3. (c) the spherical corona of continuous radio-emission.

As far as (a) is concerned we are not yet in a position to say very much. The only type of objects of extreme population 11 that we have recognized with certainty in the Galactic System as well as in other comparable systems are the globular clusters. They are very incompletely known in the Galaxy, perhaps somewhat more completely in the Andromeda nebula, but few systematic studies have been made in other systems. So far as we can tell, the Andromeda nebula and the Galactic System are comparable in the number and general distribution of globular clusters.