In calculating by means of model the pressure to be exerted on the mucous membrane at the time of inserting alginic impression material into epipharynx the pressure was found to be slight; amounting to only about 1.5 to 2.0mg Hg (2.03-2.71g/cm(2)). Next, the author compared the morphological difference of the epipharynx, in vivo, 24 hours after death, after fixing in 10% formalin, and after embedding in celloidin the decalcified specimens, by inserting alginic impression material into the rabbit epipharynx. As the result the rabbit epipharynx 24 hours after death is fairly wider than that in vivo. This seems to be due to the slackening in the tension of salpingopharyngeus muscle. In the case of epipharynx after fixing in the 10% formalin solution and that after embedding in celloidin, however, it is revealed that the epipharynx is extremely narrow. This appears to be due to the contraction of the whole tissue by fixation. Therefore, it is obvious that there would be considerable differences in the measurements after death and in vivo in such an organ as epipharynx surrounded by soft tissues, making it impossible to estimate in vivo measurements from those of cadaver. In the present experiment it has been confirmed that alginic impression material enables to represent minute morphological changes.