PHANEROGAMIA : FLOWERS. 



417 



167. 1. Gymnosperms. The process of cell-formation by which 

 the embryonal globule is produced continues on, but in very dif- 

 ferent forms, in different parts of the embryo. The apex of this 

 has acquired, through twelve cells originally formed, a definite form 

 and determinate limits externally, and retains these. At first this 

 end is bluntly rounded off, subsequently from two to twelve folia- 

 ceous organs originate (in such a manner that the extreme point 

 always remains free) simultaneously and in a circle ; in the earliest 

 condition as minute papilla?, standing on the border of the upper 

 convex surface, gradually, however, growing up beyond the point 

 (which always remains free), and then by degrees covering it up by 

 applying themselves more closely together over it : these are the 

 cotyledons or germ-leaves. Very different phenomena are exhibited 

 at the other end : there the process of cell-formation is apparently 

 continued still further on in the suspensor. The extreme cells 

 formed here always become at once more or less elongated, at 

 a somewhat later period curve away from one another, so that the 

 end of the embryo, the radicle, never has a definite boundary, but 

 appears to lose itself among very lax cells. This condition persists 

 until the full development of the embryo, which always passes, 

 through these cells, which constantly appear more lax, almost at 

 once into the four long cells of the suspensor, which remains 

 unchanged to the time of maturation of the seed. The very long 

 suspensor is, moreover, gradually compressed into a coil by the 

 growing onward of the embryo ; it may, however, be disentangled, 

 even in the ripe seed, with some care. 



The preceding exposition is from my own re- 

 searches in our native Coniferce. From the 

 beautiful analyses of the ripe seed of the Cyca- 

 dacece by L. C. Richard *, as well as from the 

 miserable figures by Gaudichaud f, it is cer- 

 tainly similar in this family also, with the dis- 

 tinction that here occur constantly only two co- 

 tyledons, which are blended up to the free points, 

 and only leave a slit on one side for the subse- 

 quent protrusion of the enclosed bud. In Viscum 

 also, according to the excellent researches of 

 De Caisne J, something similar seems to occur in 

 reference to the formation of the radicle. This 

 want of a definite limitation of the radicle essen- 

 tially distinguishes, so far as I know, the Gym- 

 nosporous from all Mono- and Dicotyledonous 

 plants, in which I have never found any thing 

 similar. 



* Commentatio Botanica de Coniferis et Cycadeis, opus posthumum ab Achille 

 Richard in lucem editum. Stuttgardt, 1826. 



f Rech. Gen. sur 1'Organogr. &c. Paris, 1841. 



j Mem. sur le Dev. du Pollen, de 1'Ovule et sur la Structure des Tiges du Gui. 

 Brussels, 1840. 



853 Abies balsaminea; A, Embryo in a very young condition : a, terminal point of the 

 axis, the future terminal bud ; b, border from which the cotyledons subsequently arise ; 



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