Die Verhältnisse, nach welchen sich die Abkömmlinge der Hybriden in der ersten und zweiten Generation entwickeln und theilen, gelten wahrscheinlich für alle weiteren Geschlechter.
The proportions according to which the offspring of the hybrids develop and divide themselves in the first and second generations probably apply to all further generations.
proportions = Verhältnisse See p. 3, s. 8.
offspring = Abkömmlinge See p. 9, s. 4.
develop and divide themselves = sich […] entwickeln und theilen Both verbs are used reflexively by Mendel, a strong indication that he thought of segregation not as a strictly combinatorial, but as a biological, and more specifically, developmental process. The conjunction of entwickeln and theilen lends additional weight to this interpretation, and is consistent with Mendel’s announcement at the beginning of his paper that his experiments will throw light on the “developmental history” (Entwicklungsgeschichte) of organisms; see p. 4, s. 1.
first and second generations = ersten und zweiten Generation Refers to what we would call F2 and F3 today (see p. 12, s. 3).
generations = Geschlechter Geschlecht can mean “generation”, but can also indicate other genealogical units, such as lineages or collateral lines. It was also used for “gender” and for “genus” (which today would usually be called Gattung). Examples for the latter uses can be found in p. 6, s. 1 and p. 43, s. 5.