This figure uses 3.6 Å resolution spectra to take advantage of their broader spectral coverage. In addition, the ordinate in this figure is in terms of "flux" instead of "rectified intensity", so that the change in the shape and slope of the continuum can be seen as a function of spectral type. In the K-type dwarfs, the spectral type may be estimated from the ratio of Ca I 4227 to Fe I 4383, in the sense that Ca I/Fe I grows toward later types. By M0, bands due to TiO become visible in the spectrum, and these strengthen quite dramatically toward later types; by M4.5 they dominate the spectrum. To exclude the possibility of systematic errors in metal-weak stars, ratios of TiO band strengths should be employed. Notice as well the development of the MgH feature at 4780. It begins in the mid-K-type dwarfs as a pointed tooth-like absorption feature, which then becomes progressively more flat-bottomed as a nearby TiO band grows in strength. A band of CaOH, a tri-atomic molecule, makes its first appearance at about M3, and contributes to a strong absorption feature by M4.5. Notice that H is in emission in the M4.5 star; many M dwarfs have active chromospheres and exhibit strong flares many times more energetic than solar flares. One of the manifestations of this is emission in the hydrogen lines.