Nach der Ansicht berühmter Physiologen vereinigen sich bei den Phanerogamen zu dem Zwecke der Fortpflanzung je eine Keim- und Pollenzelle zu einer einzigen Zelle *), welche sich durch Stoffaufnahme und Bildung neuer Zellen zu einem selbstständigen Organismus weiter zu entwickeln vermag.
According to the opinion of famous physiologists, in phanerogams one germ and one pollen cell respectively unite to form a single cell*) that is able by absorption of matter and formation of new cells to develop itself further into an autonomous organism.
physiologists = Physiologen It is unclear who Mendel had in mind here. The most likely candidate is Nathanael Pringsheim (1823–1894), who demonstrated for algae that single cells are involved in fertilisation only; see Vítězslav Orel, Gregor Mendel: The First Geneticist (Oxford: Oxford University Press, 1996), p. 88. Most other naturalists and physiologists before Mendel, including Gärtner, believed that the contributions of pollen and germ cells were unequal and that more than one pollen cell could be involved in fertilisation (see p. 24, s. 4). The footnote Mendel adds to this sentence makes it abundantly clear that he actually relies on the results of his own hybridisation experiments for the strong claim he makes in this sentence.
germ … cell = Keim- …zelle See p. 24, s. 4.
unite = vereinigen See p. 41, s. 6.
autonomous = selbstständig See p. 6, s. 1.
absorption of matter = Stoffaufnahme Bateson has “assimilation”, Sherwood “incorporation of matter”.