further research would be rewarding. Of course, scientists can rarely identify by direct observation the tbings that they are looking for; most of the time they have to be guided by indirect indices. The ebernist often first detects a compound, or even a particular functional group in its molecule, by inference from a color reaction, a revealing X-ray diffraction pattern or the formation of a characteristic precipitate. The physician must first suspect the presence of a microbe through certain clinical signs and symptoms before he can verify his diagnosis by looking for a particular organism. It is perhaps not too daring to hope that in our first efforts to clarify the role of hormones in resistance, simple, directly visible indicators might also serve us best.