mined by the reaction of the host. He further described and drew from life the formation and fertilisation of the gametes, and again showed the extrusion of part of the nucleus and the actual process of fecundation by micro- gametes.
At the same time, he completed the researches he had formerly made on a haeraogregarine of the lizard, Karyolysis lacertarum, and demonstrated that the intermediate host was a tick, Ixodes ricinus, that the larvae were infected by way of the ovary, and that the process was closely allied to those of the organism of spirillar fever in bed-bugs, and of the developmental spirochaetse of Plasmodium ziemanni in the mosquito.
More important still was his work at this time on Amoebiasis. At Rovigno, dysentery was endemic, and Schaudinn's familiarity with the reproduction of the free-living amoebae stood him in good stead in unravelling the problems of the disease. He began at once a series of simultaneous observations on many different specimens, and one of the first results which he obtained, and which, perhaps, could have been secured in no other way than by his own method of work, was the one which solved so many hitherto unexplained difficulties. He showed, as you all know, that two species of amoebae are parasitic in the human colon, which, though similar in appearance, differ widely in their life-cycles, in their reproduction, and in their pathogenicity. The research was productive of results which are now among the most familiar facts in tropical medicine, and it is unnecessary to say more than that, while carrying it out, Schaudinn did not hesitate to repeatedly infect himself by swallowing the developmental cysts both of Entamoeba coli and of Entamoeba histolytica, and that he had, in consequence, two serious attacks of dysentery.
In October, 1903, he published his famous work on the
