Unter mehr als 10,000 Pflanzen, welche genauer untersucht wurden, kam der Fall nur einige wenige Male vor, dass eine Einmengung nicht zu bezweifeln war.
Among more than 10,000 plants that were examined more diligently there were only a small number of cases in which an admixture of foreign pollen could not be doubted.
studied more diligently = genauer untersucht Both Bateson and Sherwood miss the comparative, translating “carefully examined”. The comparative suggests that Mendel also carried out hybridisation experiments that he pursued with less rigour than the ones presented in his paper.