Man sieht, wie gewagt es unter Umständen sein kann, bei Hybriden aus der äusseren Uebereinstimmung Schlüsse auf ihre innere Verwandtschaft zu ziehen.
One sees how risky it can be under certain circumstances to draw conclusions in the case of hybrids from external agreement to their inner affinity.
in the case of hybrids = bei Hybriden Bateson and Sherwood translate “of hybrids”, and append it to “external resemblances” and “internal kinship” respectively. It seems from the context, however, that Mendel speaks of the offspring of hybrids generally, including the “constant forms” among them.
inner affinity = innere Verwandtschaft Druery has “internal relations”, Bateson “internal nature” and Sherwood “internal kinship”. On “affinity” (Verwandtschaft), see p. 39, s. 7. Mendel adds a new dimension to this complex taxonomic concept; whether two forms that agree entirely in their external traits are identical or not depends on what he elsewhere calls their “inner constitution” (see p. 24, s. 8), and what we nowadays would call their genetic constitution.