Studies on Trichinella spiralis. I. Concerning the time and site of insemination of females of Trichinella spiralis. II. Time of initial recovery of larvae of Trichinella spiralis from blood of experimental animals. III. Effect on the intestinal phase of trichinosis of feeding massive numbers of irradiated trichina larvae. IV. Effect of feeding irradiated Trichinella larvae on production of immunity to re-infection. V. Tests for a strain of trichina larvae resistant to radiation.