302 DR. M. J. SCHLEIDEN ON PHYTOGENESIS. 



find the same result also in the process of the growth of the 

 entire plant. It is principally a foUaceous organ, the anther, 

 which has hitherto been studied and followed in its development 

 by many celebrated men (particularly well by Mirbel) ; and here 

 it is quite decided that the increase of cells takes place within 

 the old ones. And in this case the formative process certainly 

 coincides with that above described. R. Brown and Meyen 

 have enumerated many cases Avhere they had observed the cyto- 

 blast in very young cells of the poUen. In Pinus, Abies, Podo- 

 stemon, Lupinus and others, I have followed up completely the 

 development of pollen after Mirbel ; in Abies I have decidedly 

 observed the cellular nuclei and their development into new ceUs 

 wdthin one another i and I have never missed the cytoblast in 

 young cells. 



Now if the poUen grains are nothing more than converted leaf- 

 parenchyma, if the anther is merely a metamorphosis of the leaf, 

 we may undoubtedly 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 in reference to the later stages of the development of the 

 embryo, actual observation is infinitely difficult in this case. With 

 a view to this I have nevertheless examined a large number of buds, 

 and have convinced myself in the most decided way of the iden- 

 tity of the process both in the constantly elongating apex of the 

 axis and in the leaves, which always originate somewhat beneath 

 it. The best adapted for this purpose are the succulent plants, 

 the Aloinece and Crassulacece. Crassula portulacea seemed to me 

 most advantageous, and in this I first succeeded in separating from 

 their connexion some cells, in whose interior young cells were 

 already developed, without however entirely filhng the original 

 cell. But having once become familiar with the subject, I was 

 subsequently able to detect in all other plants these individualities 

 from among the apparently merely semi-organized chaos. An- 

 other additional circumstance here indeed presents itself, which 

 renders the subject much more difficult than with the embryo. 

 For, setting aside the smallness of the cells, their walls, in the 

 new-forming vegetable parts, still consist only of gelatine, and 

 are so delicate, that it is exceedingly difficult to separate the 

 parts intended for examination without destroying the organiza- 

 tion altogether. (Compare Plate XV. figs. 22 — 24.) 



