Development, and Structure of the Vegetable Cell. 427 
‘eell of C. glomerata render it highly probable that these septa 
originate from the mutual contact of endogenous cells, just as is 
observed in the above-described annular folds and in Gidogonium, 
and that the septum which gradually becomes visible through 
the dense layer of chlorophyll, extending from the periphery to 
the centre of the joint-cell, is not then for the first time pro- 
duced, but that its becoming visible only indicates the increasing 
thickness of the walls of the cells concerned in its formation by 
their apposition, just as has been fully described in idogonium. 
In Gdogonium it may be distinctly demonstrated that the 
absorption of the secretion-matter contained in the cells in pro- 
cess of multiplication does not take place until after the enlarge- 
ment of the endogenous daughter cells, and subsequently to the 
construction of the septum by their contact. 
In C. glomerata, in the course of normal septum-formation 
(fig. 40 a), the largest portion of the secretion-matter situated 
externally to the two enlarging new joint-cells undergoes more 
or less complete absorption when these endogenous cells have 
so far advanced in growth as to constitute a new septum by 
the apposition of their walls, the nitrogenous compounds being 
the first to dissolve. 
The absorption of the secretion-materials contained in the 
mother cell is concurrent with a new formation of them within 
the young joint-cells ; therefore in Gidogonium this new produc- 
tion only takes place after the completion of the septum, whilst 
in Cladophora, on the contrary, it happens simultaneously with, 
or even before, this period. 
If sulphuric acid, or a solution of chloride of zinc or of chlo- 
ride of calcium, be allowed to act for some time upon a specimen 
of Cladophora glomerata, and a solution of iodine be then applied 
to it, a cloudy violet-coloured slimy layer, looking like finely 
divided iodide of starch, makes its appearance between the pri- 
mary and secondary cells, resembling the lamina sometimes 
observed in the same locality in Gidogonium (p. 282) after the 
simple application of a solution of iodine to its tissues. Whether 
this material is the remains of the secretion-matter, as in Gdo- 
gonium, or is analogous to those other conditions to be discussed 
Spirogyra, are questions requiring further research to answer 
them. 
The examination of Vaucheria convinced me that the cell 
developed as a branch is formed within the stem-cell, and only 
projects from the surface simultaneously with the production of 
a branch-like process from the enveloping membrane. The same 
fact may be observed also in certain stages of the development of 
C. glomerata. The septum produced by the enlargement of two 
endogenous cells is not completed and does not become thickened 
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