[19] A "spore" is a minute reproductive particle. [20] See CONTEMPORARY REVIEW for July, 1879, p. 714. [21] Some botanists think that yeast is no true and definite kind of plant, but that it is only a conglomeration of fungoid spores of divers sorts. [22] This motion is that referred to at the bottom of page 696, in the CONTEMPORARY REVIEW for July, 1879, as _Cyclosis_. [23] Some readers may be startled at the mode here adopted of primarily dividing the Phanerogams, and may object to it as opposed to usage; but reasons will be given later for the mode of division here adopted. [24] The above-named plants may for our purpose be thus conveniently grouped together, according to the older fashion of botanists. Strictly speaking, however, they should be divided amongst several orders--_e.g._, hazel and hornbeam (_Corylaceæ_), the oak, beech, and chestnut (_Capuliferæ_), the birches (_Betulaceæ_), the willows (_Salicaceæ_), &c. [25] Containing upwards of 2500 species. THE ARTISTIC DUALISM OF THE RENAISSANCE. I. Into the holy enclosure which had received the precious shiploads of earth from Calvary, the Pisans of the thirteenth century carried the fragments of ancient sculpture brought from Rome and from Greece; and in the Gothic cloister enclosing the green sward and dark cypresses of the grave-yard of Pisa, the art of the Middle Ages came for the first time face to face with the art of antiquity. There, among pagan sarcophagi turned into Christian tombs, with heraldic devices chiselled on to their arabesques and vizored helmets surmounting their garlands, the great unsigned artist of the fourteenth century, be he Sienese or Florentine, be he Orcagna, Lorenzetti, or Volterra, painted the typical masterpiece of mediæval art, the great fresco of the Triumph of Death. With wonderful realization of character and situation he painted the prosperous of the world, the dapper youths and damsels seated with dogs and falcons beneath the orchard trees, amusing themselves with Decameronian tales and sound of lute and psaltery, unconscious of the gigantic scythe wielded by the gigantic dishevelled Death, and which, in a second, will descend and mow them to the ground; but the crowd of beggars, ragged, maimed, paralyzed, leprous, grovelling on their withered limbs, see and implore Death, and cry stretching forth their arms, their stumps, and their crutches. Further on, three kings in long embroidered robes and gold-trimmed shovel caps, Lewis the Emperor, Uguccione of Pisa, and Castruccio of Lucca, with their retinue of ladies and squires, and hounds and hawks, are riding quietly through a wood. Suddenly their horses stop, draw back; the Emperor's bay stretches out his long neck sniffing the air; the kings strain forward to see, one holding his nose for the stench of death which meets him; and before them are three open coffins, in which lie, in three loathsome stages of corruption, from blue and bloated putrescence to well-nigh fleshless