It is often pointed out that the immunological reaction turned out sometimes to positive on these who supposed not to he affected from candidiasis or histoplasmosis or turned out in some case to negative on patient. In order to elucidate these facts, the author studied the change on the titer of antigen formed in the light of skin reaction and hemoaggulutination reaction using the sensitized erythrocytes on the pathogene-inoculated rabbit. The change on the titer was noticed on the rabbit which was inoculated the pathogene into the lung through nasal inhalation on the basis of hemoaggulutination reaction; and the titer went down earlier period than the lowering of sensitivity on skin reaction. Hence the hemoaggulutination reaction is said to be more sensitive than the latter. Also it was observed that the skin reaction tock place in different way on rabbit and on man; it was noticed as redness on 24-48 hrs. after the injection on the former while it was noticed as swelling on 3 hrs. after that time on the latter.