SUMMARY.We have been investigating asexual and sexual stages in the life cycle of a ciliated protozoan,Vorticella microstoma, with the object of determining characteristic patterns at the biochemical level. In the course of our studies we have made progress in the chromatographic analysis of acid hydrolysates of the asexual (neuter) and the sexual forms. Our findings demonstrate that it is possible to obtain from the neuter stages ninhydrin‐positive patterns which are characteristically different from the patterns derived from the sexual stage. These patterns are believed to be indicative of the biochemical peculiarities of the organisms. Ninhydrin‐positive patterns of the sexual stages ofVorticella microstomaare composed of 15 bands, in contrast with 10 bands observed in the patterns of asexual stages. In regard to color, bands 1–10 in the neuters are similar to bands 1–10 in the sexuals. The difference between the two ninhydrin‐positive patterns is believed to be significant, in that it indicates the biochemical peculiarities of the respective kinds of Vorticellae. It is suggested that chromatographic analyses may lead to the identification of the substance or substances liberated by the macroconjugant for the purpose of attracting microconjugants. The methods which have been successfully used in this study may be helpful to investigators who utilize protozoa as experimental organisms. We believe the methods and results reported here may have applications in the genetics of protozoa and in biological studies devoted to metazoan