LIFE OF THE PLANT-CELL. 103 



influence of the former, assume their proper figure and arrangement, is 

 exactly the point upon which the whole knowledge of plants turns ; and 

 whosoever does not propose this question to himself, or does not reply 

 to it, can never connect a clear scientific idea with plants and their 

 life. From the total neglect of this point it is no wonder that most of 

 the notions in Botany are enveloped in a dark and formless mysticism. 



The Protococcus-cell here again suggests the natural standard by 

 which to judge of the most simple conditions. In it we may observe 

 that two new cells are formed within the cell, which lie for a time 

 loose in the mother-cell, and at last destroy it, and then become new, 

 free organisms. The same thing takes place, according to Nageli, in 

 almost all the Algce : a similar process is exhibited in the double spores 

 of the Lichens. In the Pezizce we may notice eight new cells originate 

 in a cell. In the Ferns and Equiseta the spore-cells are formed in the 

 mother-cell. In the Phanerogamia it is easy to observe the formation of 

 cell within cell : in the embryo-sac (a large cell), in the embryonic cell, 

 in which the production of new cells within the first-formed ones may 

 also be traced. In the pollen of most plants there is no doubt that free 

 cells are formed in other cells ; in the apex of the bud, and in the cambium, 

 it not unfrequently happens that new-formed cells are seen in the 

 mother-cell : almost all forms of hair entirely corroborate this view of 

 the process. Examples of this sort are exhibited in nearly every group 

 of plants, and almost in every part ; and consequently I believe that 

 the proposition based upon induction may be thus provisionally de- 

 fined : " The process of the reproduction of cells by the formation of 

 new cells in their interior is a general law in the vegetable kingdom, and 

 is the foundation of the production of cell-tissue" Respecting the way 

 in which new cells are produced, all that is necessary has been pre- 

 viously stated ( 13.). 



The figure of the incipient crystal depends upon the material of which 

 it is formed, and the physical conditions under which it originates. This 

 might, perhaps, be thus expressed in general terms : the figure depends 

 upon the nature of the material and the nature of the formative processes. 

 To apply it to the cell, as the matter and form of the originating formative 

 process are derived from the mother-cell, the latter must exert an es- 

 sential influence upon the filial-cell. The formation of the latter, how- 

 ever, is not completed in the mother-cell, but is continued after its 

 liberation therefrom, and consequently the figure of the filial-cell is 

 modified in many ways by after influences and relations. This explains 

 both the constancy of the specific figure, and the multiplicity of the 

 individual varieties. Here, consequently, we require nothing but the 

 complete analysis of the process of cell-formation in its separate elements, 

 and of the information to be derived from crystallisation (as, from a definite 

 material and determinate physical condition, a determinate figure must 

 inevitably arise), in order to subject to a scientific solution, and under 

 the simplest form, the great mystery of organic generation, upon which 

 the constancy of species, and together with it the normal conditions of 

 the whole of organic life upon the earth, depend : clearly a goal within 

 the possible attainment of the human faculties. 



The primary elements of this doctrine I gave in Muller's Archiv, 

 for the year 1 838.* It was further developed by Nageli. | Mirbel \ dis- 



* Schleiden, Botanische Beitriige, vol. i. p. 121. 

 f Schleiden und Nageli, Zeitsch. f. w. B., vol. i. part 1. 

 } Sur la Marchantia polymorpha, Paris, 1831 et 1S32, p. 32. 

 ii 4 



