124. Prof. H. Karsten on the Formation, 
striam 10. et marginem usque ad apicem), basi quoque (a seutello 
ad humeros) flavo; corpore subtus, pedibus antennisque nigris. 
Long. corp. lin. 24; lat. lin. 2. 
A species which may at once be recognized by its four flavous 
bands, each of which is broken, and, as it were, overlaps itself 
medially. 
From the Chevrolat collection; received from the Cape of 
Good Hope. 
[To be continued. | 
XIII.—Histological Researches on the Formation, Development, 
and Structure of the Vegetable Cell. By Prof. H. Karsten. 
[Continued from p. 36. | 
§ X. 
Formation of new joint-cells by the internal development of tertiary cells, 
and of the daughter cells contained within the secondary cells.—Folds 
im the wall of the mother cell. 
In the different species of the genus Spirogyra the distinctness 
with which the changes just described as undergone by the 
endogenous cells may be recognized is very variable, and it ap- 
pears even to differ in the same species at its different periods of 
development, or under different conditions of nourishment. 
Although I observed a great number of Spirogyra, it was 
especially in S. natida and S. orthospira that I saw the development 
of the nuclear cell of which I shall here endeavour to give a 
general picture ; and although this may be subject to modifica- 
tions in detail for the different species, or their particular condi- 
tions of development, it nevertheless gives the certain result 
that in these plants also the cell-multiplication is effected by 
endogenous cell-formation, as indeed was to be expected. 
If we trace, in the first place, the changes which are to be re- 
cognized in the cell-nucleus with its daughter cells, we have in 
the developmental condition represented in Plate VII.* fig. 85 
an indication of the production of the septum in the mother cell 
by the flattening of the two daughter cells which enclose the 
nucleus of the mother cell between them. 
The further development of this cell-system takes place usu- 
ally as follows :—Simultaneously with the absorption of the 
nucleus of the mother cell new cells are produced in the daughter 
cells ; the latter expand either in breadth, and then in the region 
of their central, contiguous and flattening walls, or in length; 
and at the same time their mother-cell membrane (the original 
membrane of the nucleus) seems gradually to disappear. The 
new nuclei of the two daughter cells are situated on their walls 
* The Plate here referred to will be found in the June Number. 
