  We find a trend between the mid-infrared HCN/H2O flux ratio and submillimeter
disk mass among T Tauri stars in Taurus. While it may seem puzzling that the
molecular emission properties of the inner disk (< few AU) are related to the
properties of the outer disk (beyond ~20 AU) probed by the submillimeter
continuum, an interesting possible interpretation is that the trend is a result
of planetesimal and protoplanet formation. Because objects this large are
decoupled from the accretion flow, when they form, they can lock up water (and
oxygen) beyond the snow line, thereby enhancing the C/O ratio in the inner disk
and altering the molecular abundances there. We discuss the assumptions that
underlie this interpretation, a possible alternative explanation, and related
open questions that motivate future work. Whatever its origin, understanding
the meaning of the relation between the HCN/H2O ratio and disk mass is of
interest as trends like this among T Tauri disk properties are relatively rare.
