It is well known that immunity acquired by passing through such a disease as scarlatina or small-pox persists for years, or perhaps during the remainder of life. Immunity induced by vaccination is of the same nature, but it is presumably less complete and of shorter duration than that acquired from the disease itself. Immunity induced by antitoxines is of still shorter duration. In the former case the living cells are stimulated to produce antitoxine sufficient to counteract the action of the toxines, and this ability may be persistent. In the latter case there may be some stimulation of the cells to produce antitoxine, but the animal is mostly passive, and the immunity passes off when the antitoxine introduced is exhausted.
It is consistent with the views stated above that Inheritance plays a very small part in induced and acquired immunity, whereas in natural immunity it is the predominating element. According to the views of Ehrlich and Vaillard, the male has no influence in transmitting acquired immunity to the offspring. In the case of the female any immunity conveyed is rather that of an antitoxine than of vaccination, and is evanescent. Hence vaccination is necessary in the child, even although the parents may possess an acquired immunity.
See fully in Sternberg, Bacteriology, 1892; Pasteur, Numerous papers in Comptes rendus; Report of Commission on Hydrophobia, Brit. Med. Jour., 1887; Koch, Traum. Inf. Dis., Syd. Soc. transl., 1880; Behring, Brieger, Kitasato, Ehrlich, Wassermann, Many papers in Deutsch. med. Wochenschr. and Zeitschr. f. Hygiene; Metschnikoff, Virch. Arch., xcvi., xcvii., cix., cxiii., Brit. Med. Jour., 1891, i., 213. Annales de l'Institut Pasteur, No. 9, 1894; Koux, ibid., Nos. 9 and 10, 1894; Hess, Virch. Arch., cix., ex.; Ehrlich, Zeitschr. f. Hyg. xii., 1892; Vaillard, Annales de l'Institut Pasteur, x., 1896.