He experimented on five forms which are commonly reputed to be varieties, and which he tested by the severest trial, namely, by reciprocal crosses, and he found their mongrel offspring perfectly fertile.
Arruntki aldakitzat jotzen diren bost formarekin egin zituen esperimentuak, frogarik zorrotzenaz baliatuz, hau da, elkarrekiko gurutzaketaz, eta aurkitu zuen haien ondorengo mestizuak erabat ugalkorrak zirela.