^86 Prof. H. Karsten on the Formation, 



of filaments the other cells of which exhibited the normal annular 

 folds ; and I only noticed it with clearness after the action of 

 solution of iodine and chloride of zinc upon the plant had tinted 

 the deeply penetrating fold of the cell of a dark blue colour. 

 By this means it was seen to extend very gradually and to out- 

 stretch itself, until it had fully emerged from the membranous 

 sheath and became no longer distinguishable from a cell which 

 had suddenly extended itself in the usual manner. The secondary 

 cell was contracted around its contents, as is exhibited in Pl.VII. 

 fig. 49; but sometimes also the chlorophyll and amylaceous 

 contents expanded themselves and filled the whole of the lower 

 space of the cell as far as the margin of the enveloping sheath. 



This phenomenon I once observed taking place in several in- 

 dividuals of (Edogonium grande with great uniformity, and, as the 

 evolution took place very slowly, with great certainty ; but since 

 then I have looked for similar examples in vain, and can there- 

 fore, much to my regret, contribute nothing further respecting 

 the conditions under which this interesting act of fold-construc- 

 tion takes place. 



Nevertheless it furnishes a fresh proof against the view spoken 

 of — namely, that the cellulose membrane is the external thicken- 

 ing layer (or, as Mohl's school would represent it, excretory 

 layer) of the secondary cell, — and can only be explained by the 

 developmental faculty of the independently assimilating cell-wall. 



Moreover the opinion that the normal annular fold is simply 

 an excretion from the primordial sac is completely hypothetical. 

 There is nothing to show that the secondary cell possesses in 

 the portion contiguous to the ring any other or stronger powers 

 of vegetation than in any other portions. 



Besides the well-known and frequently described development 

 of spores and gonidia, I also observed other organs, the func- 

 tions of which are still unknown to me, but which, on account of 

 their aberrant and strange developmental phenomena, certainly 

 merit more general attention ; for which reason I do not think 

 I shall be accused of precipitancy for publishing here the little 

 that I have observed respecting them. 



Bary indeed appears to have met with something similar; 

 for he has described and figured (Senckenberg Transactions, 

 yol. i.) certain "globules of decomposition '' (Zersetzungskugeln), 

 which were produced from the joint-cells of dying specimens of 

 (Edogonium capillare, (E. acrosporum, and (E. echinospermum. 

 Bary saw the aggregated mass of contents form into a globule, 

 and escape from longitudinal rents in a cell, commencing in the 

 still unthickened and soft membrane of the recently extended 

 annular fold. He more rarely noticed them escaping through 

 the old and firm cell-membrane. 



