Soweit die Erfahrung reicht, finden wir es überall bestätigt, dass constante Nachkommen nur dann gebildet werden können, wenn die Keimzellen und der befruchtende Pollen gleichartig, somit beide mit der Anlage ausgerüstet sind, völlig gleiche Individuen zu beleben, wie das bei der normalen Befruchtung der reinen Arten der Fall ist.
As far as experience reaches, we find it confirmed everywhere that constant descendants can only be formed if the germ cells and the fertilising pollen are of the same kind and hence both are equipped with the disposition to animate completely identical individuals, as is the case with the normal fertilisation of pure species.
experience = Erfahrung Mendel reports this as a widely held empirical conviction and corresponding statements can indeed be found in contemporary literature; see e.g. Franz Unger, Anatomie und Physiologie der Pflanzen (Budapest: C. A. Hartleben, 1855), p. 391. The epistemic status of this statement is complicated, though, since the constancy of traits was also used to define “pure species” in the first place; see Staffan Müller-Wille and Vitezslav Orel, “From Linnaean Species to Mendelian Factors: Elements of Hybridism, 1751–1870”, Annals of Science 64 (2007), pp. 189–190.
constant = constante See p. 5, s. 5.
of the same kind = gleichartig Bateson has “of like character”, Sherwood “alike”; see p. 41, s. 7.
germ cells = Keimzellen See p. 24, s. 4.
fertilising pollen = befruchtender Pollen In this instance, Mendel follows the widely held view that pollen plays the active part in fertilisation; cf. p. 24, s. 3.
animate = beleben Bateson and Sherwood have “create”, Druery has “vitalise”. The German verb beleben can indeed be translated as “vitalise” or “vivify” as well, which evinces that Mendel thought of the interaction of gametes as an irreducibly biological process.
pure species = reinen Arten Sherwood have “pure strains”, we follow Bateson. The term was in common use in natural history to designate species that exhibited no hereditary variation; see e.g. a passage in Carl Friedrich Gärtner, Versuche und Beobachtungen über die Bastarderzeugung im Pflanzenreich (Stuttgart: Hering, 1849), Mendel Museum, Collection of the Augustinian Abbey, p. 64, which Mendel marked with a double line at the margin. It should be noted, however, that Gärtner, as well as Kölreuter, distinguished between “pure species” and “varieties”, and believed that hybrids of the latter behaved differently. On Mendel’s species concept, which abolishes this distinction, see p. 6, s. 14.