Development, and Structure of the Vegetable Cell. ^^1 



cell 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 (Edogonium, 

 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 (Edogonium. 



In (Edogonium 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 j therefore in (Edogonium 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 (Edogonium (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 (Edo- 

 gonium, or is analogous to those other conditions to be discussed 

 in 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 



28* 



