a few particles. The former is reflected in the decrease in $S(q^*)$. Significantly, upon increasing the attraction from zero, the decrease in the peak height starts at the point of the melting of the repulsive glass, and continues until we enter the attractive glass region, whereupon the peak height remains constant (inset Fig. \[fig:sqLo\](a)).

The increased heterogeneity is reflected in a rise in the SSF at low $q$, Fig. \[fig:sqLo\](b). The smallest $q$ we have studied was $q_{\text{min}}R=1.50$, corresponding to a length scale of about 4 particle radii. The value of $S(q_{\text{min}})$ increases nearly exponentially with the polymer concentration between samples A–E (inset Fig. \[fig:sqLo\](b)), and thereafter remains constant. The increased density fluctuations at this length scale corresponds to the opening up of ‘holes’ due to particle clustering.

Note that all three features considered, $q^*$, $S(q^*)$ and $S(q_{\text{min}})$, remain virtually constant for all three attractive glass samples, F–H. Once particles drop into each others’ narrow attractive potential wells, any further [*structural*]{} changes will be hard to resolve. We shall see, however, that the [*dynamics*]{} continues measurably to evolve from sample F to sample H: in this regime of almost-touching nearest neighbors, a very small change in the structure has very 