PHYTOGENESIS. 253 



cell. A similar process occurs in the embryonal end of the 

 pollen-tube, consequently in a highly elongated cell; I shall 

 now proceed to describe the further development of the embryo. 

 After the first cells, generally few in number, are formed, they 

 rapidly expand to such an extent that they fill the pollen-tut) 

 which soon ceases to be perceptible as the original enveloping 

 membrane; but at the same time several cytoblasts origin) 

 in the interior of each of these cells, and generate new eel 

 on the rapid expansion of which the parent-cells also < to 



be visible and become absorbed. The same process is repeated 

 indefinitely. But since the newlv-gcneratcd cells have con- 

 tinually less room to expand, and therefore constantly beco? 

 smaller, the previous transparency is soon lost in consequence 

 of the continual production of new cytoblasts in the interior, 

 and the tissue becoming more and more compressed; and from 

 this stage to the perfect completion of the embryo we are eon- 

 ducted by the clearly logical inference that the process thus 

 introduced continues the same, since no new force comes into 

 operation which could induce us to assume a sudden variation 

 of the vital action, more especially as we soon meet with the 

 same manifestation of the vegetative power again. 



Meanwhile the seed germinates, and the embryo becomes a 

 plant; and then indeed the question may arise, — Does the pro- 

 cess of life continue the same thenceforward in the interne- 

 and foliaceous organs? Now we are here very quickly con- 

 vinced of the negative, that is, that a formation of new cells on 

 the surface of the existing organs does not take place. The 

 surface is always smooth, and generally covered in a very early 

 state with a kind of epidermis, the outer layer being more 

 transparent and almost as clear as water; and we never find 

 even an indication of a newly-formed cell upon the surface. 



But if the embryo be the type of the entire plant, and the 

 latter do not present anything which is not a repetition of its 

 organs, if we have found the growth of the embryo to con-i>t 

 only in the formation of cells within cells, we may then expect 

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

 whole plant. It is especially a foliaceous organ, the anther, 

 which has hitherto been studied and followed in its develop- 

 ment by many celebrated men (particularly well by Mirbel 

 and here it is quite decided that the increase of cells takes 



