One very astonishing and revolutionary fact discovered by Schaudinn we must, however, especially point out. Medical men have long been acquainted with the spirillum, or spiral threads, discovered by Obermeyer in the blood of patients suffering from the relapsing fever of eastern Europe. These were universally and without question regarded as Bacteria (vegetable organisms) and referred to the genus “Spirochæta” of Ehrenberg. They were called _Spirochæta Obermeieri_; and relapsing fever was held to be a typical case of a bacterial infection of the blood. It is now shown by Schaudinn that the blood-parasite spirochæta is a phase of a trypanosome (fig. 54); that it has a large nucleus and a micronucleus or blepharoplast, neither of which are present in the spiral Bacteria; and, further, that it alters its shape, contracting so as to present the form of minute oval or pear-shaped bodies, each provided with a larger and a smaller nucleus (fig. 54, E, F). These oval bodies are often engulfed by the colourless corpuscles (phagocytes) of the blood; and it is in the highest degree probable that in this condition they have been observed in some tropical diseases without their relation to the spiral forms being suspected. The corpuscles lately described by Leishman, in cases of a peculiar Indian fever, are very probably of this nature, as are also similar bodies recently described in Delhi sore. On the whole, it may safely be said that the researches of Dr. Schaudinn, of which only a preliminary account has yet been published, have widely modified our conceptions as to these blood-parasites, and must lead to important discoveries in regard to diseases caused by them in mammals and in man. [Illustration: FIG. 55. _Trypanosoma Ziemanni_, from the blood of the little owl. The stages shown in Figs. 52-54 are passed inside the gnat. The spiral and pear-shaped bodies of Fig. 54 pass from the gnat’s proboscis into the blood of the little owl, and grow there into the large forms here figured. A, B, and C are females, destined to be fertilized by spermatozoa (see Fig. 21) when swallowed by a gnat. D and E are male Trypanosomes, which will give rise each to eight fertilizing individuals or spermatozoa as shown in Fig. 56--when swallowed by a gnat.]