»8» • Prof. H. Karsteft on the Formation, 



destitute of any solid contents, and prior to the origin of any of 

 the other varieties of secretion-vesicles (fig. 29). 



In " resting " vegetative cells, i. e. in those which for a long 

 time continue apparently unchanged, and which present no new 

 formation of cells for the purpose of multiplication (neither 

 vegetation- nor reproductive cells), there nevertheless occurs a 

 continuous, though a very tardy, regeneration of the cells them- 

 Bclves. 



Whilst the external primary cell-membranes are being dis- 

 solved, and replaced by the thickening membranes of the se- 

 condary cells, nuclear cells, long persistent in an embryonic 

 condition, increase in size and assume the functions of secondary 

 cells. The secretory materials contained in these (consequently 

 exterior to the nuclear cell) are dissolved during this develop* 

 inent of the nucleus, and within the nuclear cell, which has 

 Reached the dimensions of the mother cell, other similar secretory 

 vesicles become developed. 



In consequence of this development of the nuclear cells, secre- 

 tion-vesicles are found not only on the outside of the two 

 daughter cells, but also of the secondary cells, of the (Edogomum 

 joint-cells at certain stages of development. These secretion- 

 Cells are usually starch-globules ; for the chlorophyll was the first 

 displaced and lost. (PI. VII. fig. 63, as seen after the action of 

 tt weak solution of glycerine.) 



In many cells a weak aqueous solution of iodine shows the 

 presence of starch in solution betwixt the inner membranes of 

 the cell. Mohl mentions this circumstance, and describes this, 

 together with other allied structures, as a mucilaginous deposit 

 around the primordial layer coloured blue by iodine (Botanische 

 Zeitung, 1855, p. 732). 



Before the application of the iodine, this layer has the appear*^ 

 ance of a turbid solution of gum or mucus, but afterwards forms 

 a clear transparent fluid : it therefore behaves like finely divided 

 starch. 



The two newly formed joint-^cells, after the production of the 

 septum by their apposition, cannot again be separated by the 

 agency of endosmotic media, nor do they become detached 

 thereby from the enclosing secondary cells of the mother cell. 



If such cells are allowed to remain in saline or acid solutions, 

 or in glycerine, &c., the membrane of the secondary cells en». 

 closing the new cells and other contents loosens itself from the 

 primary cell of the joint that is undergoing fission, and collects 

 into a mass along with the whole of the contents in the interior 

 of the cell : in this condition it shows no cellulose reaction. 



It is not until after the further advance of the absorption of 

 the secretory matters which occur outside the young joint-cells, 



