MisceUaneoKS. 155 



pense of the vitellus, witliia its homogeneous and amorphous envelope 

 — the viteUine membrane. 



" 2. Referrmg to cryptogamic plants, nothing is more striking than 

 the identity between the segmentation of the contents of the spores 

 for the development of sporules, or the division of the contents of the 

 latter for the formation of embryonary cells and the like jjhaino- 

 menon in animals (see the works of Thuret and Decaisne). More- 

 over, one cannot hesitate to com2)are the spores or the sporules of 

 cryptog-amic pla,nts with the ovule of animals, — their homogeneous 

 enveloiie with the vitelline membrane, and thfir granular contents 

 with the vitellus. With respect to the differences which, in this 

 point of view, exist between the formation of spores and their ger- 

 mination among fungi and microscopical algae, they constitute no 

 more than mere varieties of the phsenomenon of segmentation, and 

 such are to be met with in higher organizations, and the gradual 

 simi)lification or degradation may be traced. 



" 3. In phanerogamous plants the embryonary sac appears in the 

 form of a transparent cell in the nucleus of the ovule : its contents 

 very soon become granular and form a true vitellus. After fecun- 

 dation two nuclei make their appearance, around which the granular 

 matter of the vitellus collects itself ; in the line of separation between 

 these two spherical bodies a dissepiment appears, indicating the for- 

 mation of the membrane to envelope each of them and to transform 

 them into embryonary cells : this effected, each of the latter subdivide 

 into two, and so on. Here it is still evident that the embryonary cells 

 are formed after the same fashion as in animals, and these facts show 

 that the embryonar}' sac of j)hanerogamous plants is the only part of 

 them comparable with the ovum of animals. We have in it the true 

 ovule of plants, in the form of a cell, soon displaying a homogeneous 

 envelope or vitelline membrane, and a granular interior or vitellus. 

 As to the primine, secundine, and nucleus or tercine, these are but 

 organs composed of cellular tissue, organs of protection or of nutri- 

 tion, and accessory only to the essential part — the ovule. 



*' B. Analogy between the product of the male organs and that of the 

 ovaries of the female among plants and animals, and identity between 

 the mode of formation in the male ovule of the grains of pollen or of 

 spermatozoa, and that of the embryonary cells in the female ovule. 



" 1. All botanists agree in describing, in each half of the young 

 anther, the development of large cells, out of which the grains of 

 j)ollen are formed, and vvliich are called the parent-cells of pollen, or 

 j)ollen-utricles. These utricles are made up of granular contents, 

 constituting a true vitellus analogous to that of the vegetable ovule, 

 and inclosed by a homogeneous wall, or vitelline membrane. In 

 the vitellus, at first two, and afterwards four nuclei appear, around 

 which the vitelline granules congregate, in such a way as to form 

 so many small spheres, each of which soon becomes furnished with 

 an inclosing envelope. These cells thus formed, after some modi- 

 fication of their walls, constitute grains of pollen. The analogy iu 

 the formation of the latter to that of the erabiyonary cells iu the 

 ovule, or embryonary sac of the plant, cannot fail to be observed, iu 



