128 Prof. H. Karsten on the Formation, 



the inner wall of the membrane of the secondary cell, which ia 

 then likewise engaged in development. But afterwards, when a 

 more active assimilative energy is acquired by the previously 

 resting nuclear cell for the purpose of its i)rogre3sivc or retro- 

 grade metamorphosis, or when daughter cells are developed by 

 the side of it, the secretion-vesicles separate from the wall of 

 the secondary cell, and either float in the cell-juice or sink 

 down upon the endogenous cells which are in a state of ab- 

 sorbent activity, and in the fluid contents of which new secre- 

 tion cells are produced, at tirst floating in the cell-juice, but 

 subsequently adhering to the inner surface of the secondary 

 cell-membrane. 



The vesicles in the products of decomposition of the con- 

 tents of the mother cell and daughter cells, mentioned at 

 p. 30, indicate the occurrence of such a regeneration of the 

 secretion-cells, simultaneously with those of the endogenous 

 tissue-cells. The vesicles containing chlorophyll, however, can 

 never be proved with certainty to be at the same time con- 

 tained in both the mother cell and the daughter cells. Under 

 the conditions assumed, it seems to me that they would clothe 

 the outer and inner surfaces of the membranes of the daughter 

 cells in such a manner as to correspond with each other. 



Moreover some phenomena seem to show that, simulta- 

 neously with the absorption of the chlorophyll of the mother 

 cell, it is again re-formed in the enlarged daughter cells, which 

 completely fill the mother cell (figs. 74 and 76) ; but these 

 do not prove the fact quite satisfactorily. 



Thus, simultaneously with the absorption of the chlorophyll- 

 sac over the "new septum (fig. 74), a new formation of chloro- 

 phyll is perceived near this spot, and, by this, a prolongation 

 of the separated extremities is produced, of such a nature that 

 the one extremity grows more to the right, and the other more 

 to the left at the periphery of the new septum. This newly 

 formed chlorophyll is always of a lighter green colour than the 

 old sac, and of course does not contain the large starch-vesicles. 

 That these are newly formed parts is evident, but it cannot be 

 determined whether the appearances are due, as seems probable, 

 to the prolongation of a new sac situated within the daughter 

 cell beneath the old sac, or to the direct prolongation of the 

 partially absorbed sac itself. 



By the action of solution of glycerine or chloride of calcium 

 upon cells in course of septum-formation (figs. 74 and 70), 

 phenomena are produced very similar to those observed in the 

 cell before division (figs, 78 and 79), but very difi'erent in their 

 nature. 



In the case represented in figs. 78 and 79, the delicate 



