Das ist bekanntlich nicht der Fall, da gerade unter diesen nicht blos die verschiedensten, sondern auch die veränderlichsten Formen gefunden werden.
This, however, is not the case, as we know, because it is precisely among these forms that not only the most diverse, but also the most variable forms are found.
as we know = bekanntlich See p. 29, s. 7. In this and the previous sentences Mendel repeats, and even reinforces, an argument made by Charles Darwin at the beginning of the first chapter in his Origin of Species. The German translation with which Mendel worked contains a mark at the beginning of the corresponding passage, which reads in the original: “It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organisation has once begun to vary, it generally continues to vary for many generations. No case is on record of a variable being ceasing to be variable under cultivation” (Charles R. Darwin, On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, 3rd ed., London: John Murray, 1861, pp. 8–9; cf. Charles R. Darwin, Über die Entstehung der Arten im Thier- und Pflanzen-Reich durch natürliche Züchtung, oder, Erhaltung der vervollkommneten Rassen im Kampfe um’s Daseyn, 2nd ed., transl. by H. G. Bronn, Stuttgart: Schweizerbart, 1863, Mendel Museum, Collection of the Augustinian Abbey, 17).
most diverse = verschiedensten; most variable = veränderlichsten Formen See p. 36, s. 8. Bateson contrasts “varied” with “variable”. Mendel seems to distinguish the degree of difference from its likelihood to occur.
forms = Formen See p. 3, s. 8.