Of Various extraction substances of Shigella sonnei, the author studied the chemical natures, the hemolytic specificity and the hemolysis by various diluted fractions, and, in addition to these, comparatively studied the natures of various extraction substances of S and R types. The results are briefly summarized as follows: 1) As for the chemical natures of various fractions, particularly of nucleic acids, the nucleic acid extracted with phenol was fairly purer than nucleic acid II extracted with saline and weak alkaline solutions and deproteinized by chloroform-gel and trypsin digestion method. 2) In the hemolysis, hemolytic titer of nucleic acid group substances rised with the progress of purification procedures; this fraction was considered to be a significant one as the antigen. 3) In the hemolysis by various concentration of the antigen, no difference was observed between those of chick and rabbit red cells by the 1mg/ml purified nucleic acid II, but a clear differnce existed between the two by 10γ/ml of it. Chick red cells were better sensitized by nucleic acid group substances than Boivin's substance, and rabbit red cells showed a reversse relationship. 4. As for the S and R type difference, polysaccharide substances showed a specific difference; the CF and Boivin's substances of S type showed a stronger red cell sensitization those of R type.