Atropine (C17H21N03) is another poisonous alkaloid of important use in connection with the eye. An exceedingly minute quantity locally applied causes the pupil of the eye to enlarge, by relaxation of the surrounding muscles, and thus makes possible an examination of internal parts which are ordinarily invisible. The alkaloid is obtained from the leaves and roots of belladonna (Fig. 175) a very poisonous plant.

Fig. 175. Belladonna (Atropa Belladonna, Nightshade Family, Solanaceoe). A, flowering branch. B, flower. C, same, cut vertically. D, stamen. E, stigma. F, fruit. G, seed. (v. Wettstein.) Perennial herb growing about 1 m. tall, very poisonous in every part; leaves dull green; flowers dull purple; fruit cherry like, from green becoming red and dark purple. Native home, Europe and India.

Fig. 175.-Belladonna (Atropa Belladonna, Nightshade Family, Solanaceoe). A, flowering branch. B, flower. C, same, cut vertically. D, stamen. E, stigma. F, fruit. G, seed. (v. Wettstein.)-Perennial herb growing about 1 m. tall, very poisonous in every part; leaves dull green; flowers dull purple; fruit cherry-like, from green becoming red and dark purple. Native home, Europe and India.