Ausserdem wurden noch mehrere Experimente mit einer geringeren Anzahl Versuchspflanzen durchgeführt, bei welchen die übrigen Merkmale zu zwei und drei hybrid verbunden waren; alle lieferten annähernd gleiche Resultate.
In addition, several experiments were carried out with a smaller quantity of experimental plants, in which the remaining traits were joined in hybrid fashion in twos and threes; all gave approximately identical results.
quantity = Anzahl See p. 3, s. 8.
remaining traits = übrigen Merkmale That is, the remaining traits of the seven traits listed on p. 8.
joined in hybrid fashion = hybrid verbunden Bateson has “united as hybrids”, we follow Sherwood’s elegant solution. Hybrid is used as an adverb in this instance (to be literal, one would have to translate “joined hybridly”) . The sentence reveals clearly, that Mendel thought of hybridisation as a process that affects particular traits, not whole organisms. On the term verbunden, see p. 10, s. 14.
were = waren The manuscript originally had wurden, which Mendel changed to waren, thus introducing a subtle change that is difficult to translate: wurden verbunden would have implied a subject (Mendel, obviously) actively joining the traits; whereas waren verbunden just describes the state of being joined. So “were joined” should not be read as passive voice.