Within the highest division of the animal kingdom, namely, the Vertebrata, we can start from an eye so simple, that it consists, as in the lancelet, of a little sack of transparent skin, furnished with a nerve and lined with pigment, but destitute of any other apparatus.
Animalien erreinuko dibisio nagusiaren barruan, hau da, ornodunenean, abiapuntuan begi oso xumea aurkitzen dugu; izan ere, anfioxoan bezala, nerbio batez horniturik eta pigmentuz jantzirik, baina beste aparaturik gabe dagoen mintz gardenezko zakutxo bat besterik ez da.