[Illustration: FIG. 54.--_Spirochæta duttoni_. _a_, blood form showing slight membrane; _b_, granules or coccoid bodies clearly formed within the organism; _c_, beginning of extrusion of coccoid bodies in the tick. (After Fantham.)] A little later in 1905, Koch stated that spirochætes from the gut of the tick penetrated the gut wall and tissues and found their way into the eggs in the ovary. Koch figured tangled masses of spirochætes as occurring in the tick eggs. He found ticks infective to the third generation. He thought that the infection was spread by the salivary fluid of the tick, in the act of biting. (This is now known to be incorrect.) Markham Carter (1907) corroborated Koch’s work on the spirochætes in the tick eggs, and they have been seen since by Kleine and Eckard (1913). Sir William Leishman,[147] in 1909–10, found that at ordinary temperatures the salivary glands of infected ticks (_O. moubata_) were not themselves infective, and that the infection occurred by way of the ticks’ excretion. The spirochætes (contained in the ticks’ excrement) found their way into the vertebrate host through the wound made by biting. While feeding, ticks pass large quantities of clear fluid from the coxal glands; in this fluid an anticoagulin occurs. Some of the ticks also pass thick, white Malpighian secretion, that is, excrement, towards the end of the feed. Leishman, using experimental monkeys, showed that if infected ticks were interrupted while feeding, then no infection resulted in the monkeys. If, however, the ticks were allowed to finish their feed, and the Malpighian secretions were passed, then the experimental monkeys became infected. Fantham[148] and Hindle[149] (1911), independently, have repeated the experiments with mice. [147] _Journ. Roy. Army Med. Corps_, xii, p. 123; _Lancet_ (1910), clxxviii, p. 11. [148] _Annals Trop. Med. and Parasitol._, v, p. 479. [149] _Parasitology_, iv, p. 133. Leishman’s methods and results may be summarized thus: Saline emulsions of the organs of infected ticks were made, after the organs had been most carefully dissected out. The ticks were first kept for several days at certain constant temperatures, such as 24° to 25° C. or blood heat, 37° C. The saline emulsions of the organs were inoculated, separately, into experimental animals, and the results recorded:-- At 24° C. At 37° C. Salivary glands Negative Positive Malpighian tubules Positive Positive Gut and contents Positive Positive Excrement Positive Positive Genital organs Positive Positive Coxal fluid is usually negative; thick, white excrement from Malpighian tubes is positive.