constant = constanten See p. 5, s. 5.

dominating = dominirende See p. 10, s. 14.

recessive = recessive See p. 10, s. 14.

hybrid form = Hybridform See p. 15, s. 7.

united = vereinigt Bateson has “conjoined”; see p. 41, s. 6.

expression = Ausdruck Druery has “formula”, which Bateson then replaced with “expression”, just like Sherwood. Druery had a point, though. The term Ausdruck was commonly used by German mathematicians in the sense of “formula”; see, for example, Andreas von Ettingshausen, Die combinatorische Analysis als Vorbereitungslehre zum Studium der theoretischen höhern Mathematik (Vienna: Wallishausser 1826), p. 2 and passim.

A + 2 Aa + a Mendel introduces his notation system in this sentence. At this stage, however, he is only using it to represent his empirical finding of the 1 : 2 : 1 segregation ratio, unlike at the end of Section 7, where he uses the same notation to develop a mathematical model. It should also be noted that he writes A + 2Aa + a and not AA + 2Aa + aa, as genticists would have it today. For him, the symbols do not represent internal genetic states of plants with respect to certain traits, but rather how these traits will behave in offspring. A and a will have offspring which remains “constant” with respect to the trait, while Aa produces offspring that will segregate again with respect to the trait (which hence is “hybrid”). This is also the case later on when he starts investigating polyhybrid crosses (see p. 30, s. 7 for further discussion of this important point.) Of the hybridists Mendel cites at the beginning of his paper, only Max Wichura used a notation system, but it only consisted of small letters, and these designated the varieties crossed, not traits; see Max Ernst Wichura, Die Bastardbefruchtung im Pflanzenreich, erläutert an den Bastarden der Weiden (Breslau: E. Morgenstern, 1865), pp. 8–11. Since Wichura’s book came out in the same year as Mendel presented his paper, it is unlikely to have served as a source of inspiration for Mendel’s notation system. Carl Nägeli’s papers on plant hybrids, which adopted Wichura’s notation system (but using capital letters, and, in addition, numbers to indicate the proportion of each variety in a cross) only came out in 1866; see Carl Nägeli, Botanische Mittheilungen, Bd. II (München: F. Straub, 1866), esp. pp. 239–248. The source for Mendel’s notation system is therefore more likely to be mathematical; see p. 21, s. 2.

developmental series = Entwicklungsreihe Both Bateson and Sherwood only have “series”; the verb entwickeln (“to unfold”, or “unwrap”) from which the noun Entwicklung is derived, did not only have a biological meaning (see p. 3, s. 3), but was used by mathematicians as well to designate operations by which “calculations, which are to be performed on a whole, are carried out on respective parts” (Jacob and Wilhelm Grimm, Deutsches Wörterbuch, online-edition, s.v. “entwickeln” (1859). Thus, if two sums are to be multiplied, one proceeds by multiplying in successive steps. (A + B) × (A + B), for example, can be calculated by first multiplying A with (A + B), then B with (A + B), and finally adding the results AA + AB and BA + BB to yield AA + 2AB + BB. The textbook in combinatorics by Mendel’s teacher at the University of Vienna, Andreas von Ettingshausen (1796–1878) routinely uses entwickeln and Entwickelung in this sense, but not, as far as we could see, the exact term Entwicklungsreihe; see Andreas von Ettingshausen, Die combinatorische Analysis als Vorbereitungslehre zum Studium der theoretischen höhern Mathematik (Vienna: Wallishausser 1826), passim.

two differing traits each = je zweier differirender Merkmale Bateson has “two differentiating characters”, Sherwood “pair of differing traits”; see p. 9, s. 1.