254 CONTRIBUTIONS TO 



place within the old ones. It is also certain that in this case 

 the formative process accords with that above described. R. 

 Brown and Meyen have enumerated many instances where 

 they observed the cytoblast in very young pollen-cells. In 

 Pinus, Abies, Podostemon, Lupinus and others, I have traced 

 the development of the pollen after Mirbel perfectly; I have 

 distinctly observed the cell-nuclei and their development into 

 new cells within one another in Abies, never having missed the 

 cytoblast in young cells. 



Now if the pollen-grains be nothing more than converted 

 leaf-parenchyma, if the anther be merely a metamorphosis of 

 the leaf, we may certainly infer inversely that the process 

 which we have observed in it, and which characterized the 

 formation of the embryo and cotyledons (as prototypes of the 

 leaf) will be again found in all foliaceous organs. For the 

 same reason which was stated with respect to the later stages 

 of the development of the embryo, actual observation is infi- 

 nitely difficult in this case. I have nevertheless examined a 

 great many buds in reference to this point, and have most 

 decidedly convinced myself of the identity of the process both 

 in the constantly elongating apex of the axis, and in the leaves 

 which always originate somewhat beneath it. Succulent plants, 

 the Aloinece and Crassulacece, are best adapted for this purpose. 

 Crassula Portulaca seemed to me most advantageous, for in it 

 I first succeeded in separating some cells from their connexion, 

 in whose interior young cells were already developed, without, 

 however, entirely filling the parent-cell. But having once be- 

 come familiar with the subject, I was afterwards able to detect 

 these individualities from amongst the apparently semi-organised 

 chaos in all other plants. Another circumstance indeed pre- 

 sents itself here, which renders the subject much more difficult 

 than in the case of the embryo. For, independently of the 

 minuteness of the cells, their walls, in those parts of the plant 

 which are just newly formed, still consist merely of jelly, and 

 are so delicate that it is exceedingly difficult to separate the 

 parts intended for examination without completely destroying 

 the organization. (Compare plate I, figs. 22-4.) 



This process is more easily perceptible in articulated hairs, 

 and in such as have a head consisting of several cells, where 

 the same appearances which I have so frequently observed in 



