How many of the birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called, geographical races!
Ipar Amerika eta Europako zenbat txori eta intsektu, elkarren artean alde nimiñoak dituztenak, ez ote dituen sailkatu naturalista gailen batek dudazko espezietzat eta beste batek aldakitzat, edo sarri deitzen zaien moduan arraza geografikotzat!