280 Prof. H. Karsten on the Formation, 



Nageli urges, iu opposition to the notion of the formation of 

 free cells in the fluid contents of a cell laden with various solid 

 matters, that changes must have been observable in the solid 

 contents adhering to the wall of the mother cells, should these 

 become dissolved in the mother cell and afterwards organized 

 anew in the daughter cells. 



Well founded as is this supposition of Nageli's as to the meta- 

 morphosis, the notion that such a metamorphosis does not take 

 place is equally unfounded. Indeed, in my essay 'De Cella 

 vitali^ (1843, p. 71), and elsewhere, I have maintained the oc- 

 currence of those conditions subsequently called in question by 

 Nageli, asserting, as a result of my observations, that the secre- 

 tion-material contained within the mother cell serves as nutritive 

 matter for the ensuing generation, A conviction of the entire 

 correctness of this statement, and of its high importance for the 

 right understanding of cell-life, may be most readily attained by 

 the examination of the species of CEdogonium, which, on account 

 of their remarkable tenacity of life (in which they almost equal 

 Conferva glomerata), are particularly well adapted for being 

 observed continuously under the microscope during the successive 

 stages of their process of growth. 



Indeed the entire cell-contents of the joint-cell, which has been 

 recently divided in the manner described into two portions, are 

 now found interposed between the outer surface of the two 

 daughter cells and the inner aspect of the wall of the mother 

 cell. The large, thin-walled, non-nucleated cells (vesicles), filled 

 with transparent fluid, existing at the time of the growth of the 

 daughter cells, are at this period no longer present ; indeed they 

 disappear during the first stage of development of the young 

 daughter cells, to which they probably serve as nutritive matter. 

 On the contrary, the chlorophyll and the usually large starch- • 

 granules met with in the difi'erent species of (Edogonium, in vari- 

 able quantity according to external vital conditions, are rather 

 rapidly dissolved during the growth and the thickening of the 

 membranous walls of the young joint-cells, in order to supply 

 nutritive material for the process of assimilation of the cell-walls 

 as well as for the new generation of cells and of secretion-vesi- 

 cles in process of formation within the two daughter cells. This 

 dissolution of the starch-corpuscles is completed in about twenty- 

 four hours. 



The chlorophyll first undergoes this process of absorption, 

 and afterwards the large amylaceous corpuscles ; and then they 

 progressively reappear, but in the opposite order, in the interior 

 of the newly formed joint- cells. In the first instance, small 

 starch-corpuscles make their appearance, then the chlorophyll- 

 vesicles, and, lastly, those large hyaline vesicles which, in the 



