282 Prof. H. Karsten 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, 7. 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- 
selves. 
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 embryonie 
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- 
ment 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 Cidogonium 
joint-cells at certain stages of development. These secretion- 
cells are usually starch-globules; for the chlorophyll was the first 
displaced and lost. (Pl. VII. fig. 63, as seen after the action of 
a 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. 7382). 
Before the application of the iodine, this layer has the appear- 
ance of a turbid solution of gum or mucus, but afterwards forms 
a cate 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 
ageney 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 jomt 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. 
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It is not until after the further advance of the absorption of ; 
the secretory matters which occur outside the young joint-cells, 
