PHANEROGAMIA I FLOWERS. 411 



perception of facts long since better understood. Hartig has attempted 

 a rather unfortunate defence of his "theory."* I think that I have 

 wholly settled the matter in my answer.f 



165. The pollen-tube, which has arrived in the seed-bud in 

 the manner above stated, either at once meets the embryo-sac, or 

 penetrates through the intercellular passages of the cellular tissue 

 of the nuclear papilla, which becomes somewhat more lax about 

 this time through a secretion, till it reaches the embryo-sac. 



The next phenomenon is the appearance of the end of the pollen- 

 tube inside the embryo-sac as a cylindrical or ovate utricle of 

 variable length, which has a round closed extremity toward the 

 cavity, and at the apex of the embryo-sac runs up open into the 

 pollen-tube ; the extremity soon swells up, either in such a manner 

 that the utricle produced by it (embryonal vesicle, keimblascheii) 

 consists of the whole of that part of the tube within the embryo- 

 sac, or so that between this utricle and the apex of the embryo-sac 

 there remains a cylindrical piece, of variable length, the embryo- 

 phore (keimtrdger, embryotrager,filamentum suspensorium, filament 

 suspenseur, Mirbel). The cellular tissue is developed in the 

 interior of the pollen-tube, cytoblasts originating and cells being 

 developed from them. Since new cells originate inside these cells, 

 and so forth, the embryonal vesicle, by gradual increase of size 

 and reabsorption of the parent-cells, at last becomes a little globular 

 or ovate cellular corpuscule. The pollen-tube is usually constricted 

 and closed outside the embryo-sac at the same time, and becomes 

 absorbed ; frequently also, especially where an embryophore or 

 suspensor exists, the embryonal vesicle itself becomes constricted 

 and detached, and then lies perfectly free in the apex of the 

 embryo-sac. 



The investigation of the processes described in these paragraphs is 

 without doubt, next to the origin of new cells in crowded parenchyma, 

 the most difficult task in Botany. Since I made those facts known, a 

 great deal has indeed been said on the matter; but of the many hundreds 

 of botanists, only a few have made careful investigations of the kind. 

 The following are the plants in which I have, up to this time, completely 

 examined the formation of the embryonal vesicle from the end of the 

 pollen-tube, in such a manner that I have extracted the already per- 

 fectly distinct embryonal vesicle, perceptible in the embryo-sac, in com- 

 pletely uninjured continuity with pollen-tube, still existing at least outside 

 the nucleus, quite free, and afterwards traced the origin of the em- 

 bryonal gloJDiile, by the formation of cells in the embryonal vesicle : 



Phormium tenax, Eucomis punctata, Sisyrinchium anceps, Stratiotes 

 aloides, Canna Sellowii, Maranta gibber, Orchis Morio (Plate V. figs. 10, 

 11.), latifolia (Plate VI. figs. 1,2.), pahistris, Zca Mays, Nuphar Juteum, 

 Momordica Elaterium (Plate VI. figs. 9 11.), Daphne Mezereum, Phij- 

 tolacca decandra, Polygonum orientate, Mirabilis Jalapa, longifora, 



* Ilartig, Beit, zur Entwicklungsgesohicbte dor PHanzcn. Berlin, 1843. 

 f Die neuern Einwiirfe gcgen meine Lelirc von ck-r Ik-fruchtung, c. Lcipsic, 

 1844. 



