266 Prof. H. Karsten on the Formation, 
its free surface, whereby the nucleus becomes involved in a 
duplicature of the wall, or remains free, and is at length mostly 
dissolved and lost to view. 
The majority of naturalists are now agreed that, in the vege- 
table kingdom, free cell-formation from a more or less completely 
organized nucleus of a mother cell takes place, but is of rarer 
occurrence than the production of cells by fission, according to 
the views of Mohl. 
In opposition to this hypothesis of a twofold type of cell- 
formation, I sought, in 1843, in my dissertation ‘De Cella 
vitali,’ to establish the fact that the development of organic 
forms is subject to one single law, to the recognition of which 
the observation of the phenomena of development both of vege- 
table and animal tissues had led me, and of the truth of which 1 
remain convinced now, after twenty years’ study of this question, 
alike important both for physiology and anatomy. 
Since that drochure is little known, and has been in some 
measure misunderstood, I will reproduce here those conclusions 
which relate to the question under notice :— 
1. The formation of every cell within a living organism is 
original: the cell is not divided into two new individuals by 
longitudinal or by transverse septa, or by proliferation. 2. The 
evolution of a cell does not depend upon an antecedent forma- 
tion of a solid nucleus. 3. In the first’ phase of its existence the 
cell resembles a small vesicle, very like a mere point. 4. In the 
organism the ‘cell of vegetation” does not exist in a simple form ; 
for everywhere a secondary cell is present. Every elementary 
part of the organism (the cell is deemed elementary) consists of 
a system of endogenous ceils; a member which is sometimes 
interpolated in this system of cells is the “cell of secretion.” 
5. In the secondary cell......a nucleus is found, which Schleiden 
called the formative cytoblast of the cell, but which I regard as 
a small tertiary cell retarded in its evolution. 6. In the interior 
of a cell one or several cells are developed with greater or less 
rapidity, evidently in the same manner. 7. An organism poten- — 
tially consists of one such system of cells, 7. e. a cell of reproduc- 
tion ; actually of aggregated series, every one of which may be a 
cell of reproduction ; never of a simple cell *. 
* 1, Omnis celle formatio originaria est, intra vividum organismum; 
cella dissepimentis longitudinalibus et transversalibus aut prolifera-_ 
tione in duo nova individua non disjungitur. 
2. Cellz evolutio non pendet ab antecedente solidi nuclei formatione. 
3. In primo vite sus gradu cella parva, puncto simillima vesicula ap- 
paret. 
4, In organismo non exstat cella vegetationis simplex; ubique enim — 
secundaria cella adest. Quzevis organismi pars elementaria (cella 
q. d. elementaria) ex endogenarum cellarum serie constat; mem- — 
oe 
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